Cost Management Fundamentals
原価管理基礎
Production Management Operations Grade 3 生産管理オペレーション (BC検定) · ビジネス・キャリア検定 生産管理オペレーション3級 · Written by Tokutei Pass based on the official study texts; not copied verbatim.
1. 原価管理の体系（原価企画・原価維持・原価改善）と原価計算の目的
1. The Cost Management System (Target Costing, Cost Maintenance, Cost Kaizen) and Purposes of Cost Accounting
「原価（コスト）」とは、企業が製品を生産・販売するために消費した経済価値（財貨やサービス）を貨幣額（金額）で表したものです。
"Cost" is the monetary expression of the economic value (goods and services) consumed by a company in order to produce and sell products.
「原価管理」とは、ただ過去の実績原価を計算するだけでなく、目標とする「標準原価（目標原価）」を設定してこれと「実際原価」との差異を分析し、無駄を排除して原価を引き下げる一連のPDCA活動を指します。
"Cost Management" is not merely calculating past actual costs; it refers to the continuous PDCA cycle of setting a target "Standard Cost (Target Cost)," analyzing variances against "Actual Cost," and eliminating waste to reduce costs.
現代の総合的原価管理は3つの段階で構成されます。①新製品の企画・設計段階で原価を作り込む「原価企画」、②量産段階で標準原価を達成・維持する「原価維持」、③さらなる原価低減のため標準そのものを改定・引き下げる「原価改善」です。
Modern comprehensive cost management consists of three stages: ① "Target Costing (Genka Kikaku)," which builds cost into the product at the new-product planning and design stage; ② "Cost Maintenance (Genka Iji)," which achieves and maintains standard cost during mass production; and ③ "Cost Improvement (Genka Kaizen)," which revises and lowers the standard itself for further cost reduction.
また「原価計算の目的」には、①財務諸表（損益計算書・貸借対照表）の作成、②販売価格の決定、③原価管理（コストコントロール）、④予算編成・予算統制、⑤経営の基本計画（設備投資や内外製区分の意思決定）の5つがあります。
The "Five Purposes of Cost Accounting" are: ① Preparing financial statements (Income Statement and Balance Sheet), ② Determining selling prices, ③ Cost control (cost management), ④ Budgeting and budgetary control, and ⑤ Basic management decision-making (such as equipment investment or make-or-buy decisions).
Key points
- 原価管理＝標準（目標）原価を設定し、実際原価との差異を分析して改善処置をとるPDCAサイクル活動。
Cost Management = a PDCA cycle activity that sets standard (target) costs, analyzes variances against actual costs, and takes corrective action. - 原価管理の3体系：①原価企画（設計開発段階）→②原価維持（量産での標準遵守）→③原価改善（量産での標準引下げ）。
Three pillars of Cost Management: ① Target Costing (design/development stage) → ② Cost Maintenance (adhering to standards in mass production) → ③ Cost Kaizen (lowering standards in mass production). - 製品の原価の約80%は企画・設計段階で決まるため、上流の「原価企画」が最も重要視される。
Because roughly 80% of a product's cost is determined during planning and design, upstream "Target Costing" is considered most critical.
| Word | Meaning |
|---|---|
| 原価企画・原価維持・原価改善 | Target Costing (Genka Kikaku), Cost Maintenance, and Cost Improvement |
| 標準原価と実際原価 | Standard Cost and Actual Cost |
| 原価計算の5つの目的 | Five Purposes of Cost Accounting |
2. 原価の分類（材料費・労務費・経費、直接費と間接費、変動費と固定費）
2. Classification of Costs (Material / Labor / Expense, Direct vs. Indirect, Variable vs. Fixed)
製造原価は発生形態（何を消費したか）によって、「材料費（物品の消費）」「労務費（労働力の消費：賃金・賞与・法定福利費等）」「経費（材料費・労務費以外：減価償却費・外注加工費・電力料・保険料等）」の3要素に分かれます。
By natural form of occurrence (what was consumed), manufacturing costs are divided into three elements: "Material Cost (consumption of goods)," "Labor Cost (consumption of labor: wages, bonuses, statutory welfare expenses, etc.)," and "Expenses (costs other than material and labor: depreciation, subcontract processing fees, electricity charges, insurance premiums, etc.)."
また特定の製品との関連により「直接費」と「間接費」に分かれます。どの製品のためにいくら消費したかが明確で、その製品に直接集計できる原価を「直接費」と呼び、直接集計することを「直課（または賦課）」と呼びます。
By traceability to specific products, costs are divided into "Direct Costs" and "Indirect Costs." Costs whose consumption amount for a specific product is clear and can be charged directly to that product are called "Direct Costs"; charging them directly is called "Direct Assignment (Chokka / Fuka)."
これに対し、工場建物の減価償却費や監督者の給与・共通消耗品など、複数の製品に共通して発生する原価を「間接費」と呼びます。間接費は直接作業時間や機械運転時間などの「配賦基準」で各製品へ振り分けます（これを「配賦」と呼びます）。
Conversely, costs incurred in common across multiple products—such as factory building depreciation, supervisors' salaries, and shared consumables—are called "Indirect Costs (Overhead)." Indirect costs are distributed to products using "Allocation Bases" such as direct labor hours or machine operating hours (this distribution is called "Allocation / Haifu").
さらに操業度（生産量）の増減との関連により、生産量に比例して増減する「変動費（直接材料費・外注加工費等）」と、生産量の増減にかかわらず一定額が発生する「固定費（定額法の減価償却費・固定給・火災保険料・固定資産税等）」に分かれます。
By behavior relative to operating volume (production quantity), costs are divided into "Variable Costs (direct material costs, subcontract processing fees, etc.)," which increase or decrease in proportion to production volume, and "Fixed Costs (straight-line depreciation, fixed salaries, fire insurance, property taxes, etc.)," which remain constant regardless of production volume changes.
Key points
- 形態別3要素＝材料費・労務費・経費（外注加工費や減価償却費・水道光熱費は「経費」に分類される）。
Three cost elements by form = Material Cost, Labor Cost, and Expenses (subcontract processing fees, depreciation, and utilities are classified under "Expenses"). - 直接費は特定製品へ直接集計（「直課・賦課」）し、間接費は配賦基準によって各製品へ按分（「配賦」）する。
Direct Costs are directly assigned ("Chokka / Fuka") to specific products, whereas Indirect Costs are distributed ("Allocated / Haifu") across products using allocation bases. - 変動費＝生産量に比例して増減（直接材料費等）／固定費＝生産量に関係なく一定（減価償却費・保険料等）。
Variable Costs = change in proportion to production volume (direct materials, etc.) / Fixed Costs = remain constant regardless of volume (depreciation, insurance, etc.).
| Word | Meaning |
|---|---|
| 材料費・労務費・経費（原価の3要素） | Material Cost, Labor Cost, and Expenses (the 3 cost elements) |
| 直接費（直課・賦課）と間接費（配賦） | Direct Costs (direct assignment) and Indirect Costs (allocation) |
| 変動費と固定費 | Variable Costs and Fixed Costs |
| 減価償却費と外注加工費 | depreciation expense and subcontract processing fees |
3. 原価の構成体系（製造直接費・製造間接費・製造原価・総原価・販売価格）
3. Cost Structure Hierarchy (Direct Manufacturing Cost, Manufacturing Overhead, Manufacturing Cost, Total Cost, Selling Price)
形態別3要素と直接・間接を組み合わせると、原価の階層構造が明確になります。まず「直接材料費（主要材料費・買入部品費）＋直接労務費（直接工の加工賃金）＋直接経費（外注加工費・専用金型費等）」の合計が「製造直接費」です。
Combining the three cost elements with direct and indirect classifications clarifies the cost hierarchy. First, the sum of "Direct Material Cost (main materials, purchased parts) + Direct Labor Cost (direct workers' processing wages) + Direct Expenses (subcontract processing fees, dedicated die/mold costs, etc.)" equals "Direct Manufacturing Cost (Prime Cost)."
一方、「間接材料費（補助材料費・工場消耗品費）＋間接労務費（間接工賃金・手待ち賃金・給料）＋間接経費（工場の減価償却費・電力料・保険料等）」の合計が「製造間接費」です。
Meanwhile, the sum of "Indirect Material Cost (auxiliary materials, factory consumables) + Indirect Labor Cost (indirect workers' wages, idle-time wages, factory salaries) + Indirect Expenses (factory depreciation, electricity, insurance, etc.)" equals "Manufacturing Indirect Cost (Manufacturing Overhead)."
そして「製造直接費＋製造間接費」が、工場で製品を造るのにかかった「製造原価（工場原価）」となります。なお、直接材料費以外の原価要素をまとめて「加工費」と呼ぶこともあります。
The sum of "Direct Manufacturing Cost + Manufacturing Overhead" is the "Manufacturing Cost (Factory Cost)" incurred to make the product in the factory. Note that cost elements other than direct material cost are often collectively called "Conversion Cost (Processing Cost)."
さらに、この「製造原価」に営業活動や本社管理にかかった「販売費及び一般管理費（販管費：営業員給与・広告宣伝費・発送配達費・本社役員報酬等）」を加えたものが「総原価（販売原価）」であり、「総原価＋利益」が「販売価格（売価）」となります。
Adding "Selling, General and Administrative Expenses (SG&A: sales staff salaries, advertising expenses, shipping/delivery costs, head-office executive compensation, etc.)" to "Manufacturing Cost" gives "Total Cost (Cost of Goods Sold + SG&A)," and "Total Cost + Profit" equals the "Selling Price."
Key points
- 製造直接費＝直接材料費＋直接労務費＋直接経費（外注加工費や特許権使用料など）。
Direct Manufacturing Cost = Direct Material Cost + Direct Labor Cost + Direct Expenses (subcontract processing fees, patent royalties, etc.). - 製造原価＝製造直接費＋製造間接費（工場内で発生する原価の合計）。
Manufacturing Cost = Direct Manufacturing Cost + Manufacturing Overhead (total costs incurred within the factory). - 総原価＝製造原価＋販売費及び一般管理費／販売価格＝総原価＋利益（広告宣伝費は製造原価ではなく販管費！）。
Total Cost = Manufacturing Cost + Selling, General & Administrative Expenses (SG&A) / Selling Price = Total Cost + Profit (advertising is SG&A, NOT manufacturing cost!). - 【例】直接材料費500円・直接労務費300円・直接経費100円・製造間接費200円・販管費150円・利益250円 → 製造直接費＝900円、製造原価＝1,100円、総原価＝1,250円、販売価格＝1,500円
Example: Direct materials 500 yen, direct labor 300 yen, direct expenses 100 yen, manufacturing overhead 200 yen, SG&A 150 yen, profit 250 yen → Direct manufacturing cost = 900 yen, Manufacturing cost = 1,100 yen, Total cost = 1,250 yen, Selling price = 1,500 yen
| Word | Meaning |
|---|---|
| 製造直接費と製造間接費 | Direct Manufacturing Cost and Manufacturing Overhead (Indirect Cost) |
| 製造原価（工場原価） | Manufacturing Cost (Factory Cost) |
| 販売費及び一般管理費（販管費） | Selling, General and Administrative Expenses (SG&A) |
| 総原価と販売価格 | Total Cost and Selling Price |
4. 原価計算の手順（費目別→部門別→製品別計算と補助部門費の直接配賦法）
4. Cost Accounting Procedure (By Element → By Department → By Product and the Direct Allocation Method)
原価計算は3つのステップで進めます。第1ステップは「費目別計算（第1次集計）」で、一定期間に発生した原価を直接材料費・直接労務費・製造間接費などの費目ごとに分類・集計します。
Cost accounting proceeds in three steps. Step 1 is "Cost Calculation by Element (First-Stage Accumulation)," which classifies and totals costs incurred during a period by item—such as direct material cost, direct labor cost, and manufacturing overhead.
第2ステップは「部門別計算（第2次集計）」で、製造間接費を発生した場所（原価部門）ごとに集計します。原価部門は、直接製造作業を行う「製造部門（機械加工・組立・塗装部門等）」と、それを支える「補助部門（動力・修繕・運搬・検査・工場事務部門等）」に分かれます。
Step 2 is "Departmental Cost Calculation (Second-Stage Accumulation)," which gathers manufacturing overhead by the place (cost department) where it occurred. Cost departments are divided into "Production Departments (machining, assembly, painting, etc.)" that directly perform manufacturing work, and "Auxiliary (Service) Departments (power, maintenance/repair, transport, inspection, factory administration, etc.)" that support them.
補助部門に集計された費用は、最終的に製造部門へ配賦します。このとき、補助部門相互間のサービスのやり取りを無視して、補助部門費を「製造部門のみ」へ直接配分する方法を「直接配賦法」と呼び、試験の計算で最もよく出題されます。
Costs accumulated in auxiliary departments are ultimately allocated to production departments. The method that ignores mutual service exchanges among auxiliary departments and allocates auxiliary department costs directly "only to production departments" is called the "Direct Allocation Method"—the most frequently tested allocation calculation.
第3ステップは「製品別計算（第3次集計）」で、各製造部門に集まった製造間接費を製品ごとに配賦し、製造直接費と合算して製品1単位あたりの製造原価を算出します。
Step 3 is "Product Cost Calculation (Third-Stage Accumulation)," which allocates the manufacturing overhead gathered in each production department to individual products and adds direct manufacturing costs to determine the manufacturing cost per product unit.
Key points
- 原価計算の3ステップ：①費目別計算（形態別集計）→②部門別計算（製造間接費の部門集計）→③製品別計算。
Three steps of cost accounting: ① By Cost Element → ② By Department (accumulating manufacturing overhead by department) → ③ By Product. - 製造部門＝機械・組立など製品を直接造る部門／補助部門＝動力・修繕・運搬・工場事務など製造をサポートする部門。
Production Departments = departments directly making products (machining, assembly) / Auxiliary Departments = departments supporting production (power, repair, transport, factory office). - 補助部門費の直接配賦法＝補助部門同士の配賦を行わず、製造部門の配賦基準の比率だけで各製造部門へ直接配賦する方法。
Direct Allocation Method for auxiliary department costs = ignores inter-auxiliary-department services and allocates auxiliary costs directly to production departments based solely on production department ratios. - 【例】動力部門費90万円（第1製造4,000kWh・第2製造2,000kWh・修繕補助部門1,000kWh）を直接配賦法で配賦 → 製造部門計6,000kWhで按分し、第1製造＝60万円・第2製造＝30万円
Example: Allocating power department cost of 900,000 yen (Mfg 1: 4,000 kWh, Mfg 2: 2,000 kWh, Repair support dept: 1,000 kWh) via direct allocation method → Prorated over 6,000 kWh total for manufacturing depts: Mfg 1 = 600,000 yen, Mfg 2 = 300,000 yen
| Word | Meaning |
|---|---|
| 費目別計算・部門別計算・製品別計算 | calculation by cost element, by department, and by product |
| 製造部門と補助部門 | Production Departments and Auxiliary (Service) Departments |
| 直接配賦法（補助部門費の配賦） | Direct Allocation Method (allocating auxiliary department costs) |
5. 個別原価計算と総合原価計算（月末仕掛品の完成品換算量）
5. Job-Order Costing vs. Process Costing (Equivalent Units of Ending Work-in-Process)
製品別計算は生産形態により2つに分かれます。多品種少量の「個別受注生産（造船・特注機械・金型等）」では、注文ごとの「製造指図書」別に原価を集計する「個別原価計算」を用います。
Product cost calculation is divided into two methods according to production type. High-mix low-volume "make-to-order individual production (shipbuilding, custom machinery, dies/molds, etc.)" uses "Job-Order Costing," which accumulates costs separately for each "Production Order (Job Cost Sheet)."
一方、少品種多量の「見込大量連続生産（食品・化学・家電等）」では、1か月などの「一定期間（原価計算期間）」に発生した総製造費用をその期間の完成品数量で割って平均単価を求める「総合原価計算」を用います。
Conversely, low-mix high-volume "make-to-stock continuous mass production (food, chemicals, home appliances, etc.)" uses "Process Costing," which divides the total manufacturing cost incurred during a fixed period (such as 1 month) by the quantity of finished goods produced in that period to find the average unit cost.
総合原価計算で月末に未完成の「月末仕掛品」がある場合、材料を工程の始点ですべて投入する「直接材料費」は、完成品数量と月末仕掛品数量の「そのままの個数比」で按分します。
In process costing, when unfinished "Ending Work-in-Process (WIP)" remains at month-end, "Direct Material Cost"—where all material is input at the start of the process—is apportioned using the "raw physical quantity ratio" between finished goods quantity and ending WIP quantity.
これに対し、工程の進行に応じて費やされる「加工費（労務費＋経費）」は、月末仕掛品数量に「加工進捗度（%）」を掛けた「月末仕掛品の完成品換算量＝月末仕掛品数量×加工進捗度」を用い、完成品数量との比率で按分計算します。
In contrast, "Conversion Cost (processing cost = labor + overhead)," which is expended progressively as the process advances, uses the "Equivalent Units of Ending WIP = Ending WIP Quantity × Degree of Completion (%)" and apportions conversion cost according to the ratio between finished goods quantity and ending WIP equivalent units.
Key points
- 個別原価計算＝受注生産・個別生産向き（製造指図書ごとに原価を集計）。
Job-Order Costing = suited for make-to-order individual production (accumulating costs per production order). - 総合原価計算＝見込大量連続生産向き（1か月の期間原価を完成品と月末仕掛品に按分）。
Process Costing = suited for continuous make-to-stock mass production (apportioning monthly period costs between finished goods and ending WIP). - 総合原価計算の加工費は「月末仕掛品の完成品換算量＝月末仕掛品数量×加工進捗度」を使って按分する。
Conversion cost in process costing is apportioned using "Equivalent Units of Ending WIP = Ending WIP Quantity × Degree of Completion (%)." - 【例】完成品400個・月末仕掛品200個（始点投入の直接材料費60万円） → 月末仕掛品材料費＝60万円×200÷（400＋200）＝20万円（完成品分40万円）
Example: 400 finished units, 200 month-end WIP units (direct material cost added at start: 600,000 yen) → Month-end WIP material cost = 600,000 × 200 ÷ (400 + 200) = 200,000 yen (finished goods portion: 400,000 yen) - 【例】完成品400個・月末仕掛品200個（加工進捗度50％）・当月加工費50万円 → 完成品換算量＝200×0.5＝100個、月末仕掛品加工費＝50万円×100÷（400＋100）＝10万円（完成品分40万円）
Example: 400 finished units, 200 month-end WIP units (50% conversion completion), monthly conversion cost 500,000 yen → Equivalent finished units = 200 × 0.5 = 100 units, month-end WIP conversion cost = 500,000 × 100 ÷ (400 + 100) = 100,000 yen (finished goods portion: 400,000 yen)
| Word | Meaning |
|---|---|
| 個別原価計算（受注生産・製造指図書） | Job-Order Costing (make-to-order and production orders) |
| 総合原価計算（見込大量生産） | Process Costing (continuous mass production) |
| 月末仕掛品と加工進捗度 | Ending Work-in-Process (WIP) and Degree of Completion |
| 完成品換算量 | Equivalent Units of production |
6. 標準原価計算と原価差異分析（材料費差異・労務費差異）
6. Standard Costing and Cost Variance Analysis (Material Cost Variances and Labor Cost Variances)
科学的・統計的調査に基づいて製品1個あたりの「標準単価×標準消費量」から算定した目標原価を「標準原価」と呼び、実際にかかった「実際原価」との差額である「原価差異（標準原価－実際原価）」を原因別に分析します（実際原価の方が多ければ「不利差異＝借方差異」）。
A target cost calculated from "Standard Unit Price × Standard Quantity Consumed" per product based on scientific and statistical study is called "Standard Cost"; the difference between standard cost and actual cost incurred—the "Cost Variance (Standard Cost － Actual Cost)"—is analyzed by cause (when actual cost exceeds standard cost, it is an "Unfavorable Variance = Debit Variance").
「直接材料費差異」は2つの原因に分解します。1つ目は購入価格の高騰等による「価格差異＝（標準単価－実際単価）×実際消費量」です。
"Direct Material Cost Variance" is broken down into two causes. First is the "Price Variance = (Standard Unit Price － Actual Unit Price) × Actual Quantity Consumed," caused by fluctuations in purchase prices.
2つ目は現場での歩留まり悪化や使いすぎによる「数量差異＝（標準消費量－実際消費量）×標準単価」です。
Second is the "Quantity (Usage) Variance = (Standard Quantity Consumed － Actual Quantity Consumed) × Standard Unit Price," caused by poor material yield or overuse on the shop floor.
同様に「直接労務費差異」も、「賃率差異＝（標準賃率－実際賃率）×実際作業時間」と、現場の作業能率による「作業時間差異（能率差異）＝（標準作業時間－実際作業時間）×標準賃率」の2つに分けて管理責任を明確にします。
Similarly, "Direct Labor Cost Variance" is separated into two components to clarify management responsibility: the "Wage Rate Variance = (Standard Wage Rate － Actual Wage Rate) × Actual Direct Labor Hours" and the "Labor Efficiency (Time) Variance = (Standard Direct Labor Hours － Actual Direct Labor Hours) × Standard Wage Rate."
Key points
- 実際原価が標準原価を超過した場合（コストオーバー）は「不利差異（マイナス）」、標準より安く済んだ場合は「有利差異（プラス）」。
When actual cost exceeds standard cost (cost overrun), it is an "Unfavorable Variance (negative)"; when actual cost is lower than standard, it is a "Favorable Variance (positive)." - 直接材料費：価格差異＝（標準単価－実際単価）×実際数量／数量差異＝（標準数量－実際数量）×標準単価。
Direct Material Cost: Price Variance = (Standard Price － Actual Price) × Actual Quantity / Quantity Variance = (Standard Quantity － Actual Quantity) × Standard Price. - 直接労務費：賃率差異＝（標準賃率－実際賃率）×実際時間／作業時間差異＝（標準時間－実際時間）×標準賃率。
Direct Labor Cost: Rate Variance = (Standard Rate － Actual Rate) × Actual Hours / Time (Efficiency) Variance = (Standard Hours － Actual Hours) × Standard Rate. - 【例】直接材料費（標準単価400円/kg・実際単価420円/kg、標準消費量500kg・実際消費量480kg） → 価格差異＝（400－420）×480＝－9,600円（不利差異）、数量差異＝（500－480）×400＝＋8,000円（有利差異）
Example: Direct materials (standard price 400 yen/kg, actual price 420 yen/kg; standard quantity 500 kg, actual quantity 480 kg) → Price variance = (400 − 420) × 480 = −9,600 yen (unfavorable), Quantity variance = (500 − 480) × 400 = +8,000 yen (favorable) - 【例】直接労務費（標準賃率1,500円/時間・実際賃率1,600円/時間、標準時間200時間・実際時間210時間） → 賃率差異＝（1,500－1,600）×210＝－21,000円（不利差異）、作業時間差異＝（200－210）×1,500＝－15,000円（不利差異）
Example: Direct labor (standard wage rate 1,500 yen/h, actual rate 1,600 yen/h; standard hours 200 h, actual hours 210 h) → Wage rate variance = (1,500 − 1,600) × 210 = −21,000 yen (unfavorable), Labor efficiency variance = (200 − 210) × 1,500 = −15,000 yen (unfavorable)
| Word | Meaning |
|---|---|
| 標準原価計算と原価差異（有利差異・不利差異） | Standard Costing and Cost Variance (favorable vs. unfavorable variance) |
| 価格差異と数量差異（直接材料費） | Price Variance and Quantity Variance (direct material cost) |
| 賃率差異と作業時間差異（直接労務費） | Wage Rate Variance and Labor Efficiency / Time Variance (direct labor cost) |
7. CVP分析（損益分岐点・限界利益）と損益計算書の利益段階
7. CVP Analysis (Break-Even Point, Contribution Margin) and Income Statement Profit Stages
原価（Cost）・営業量（Volume）・利益（Profit）の関係を分析する手法を「CVP分析（損益分岐点分析）」と呼びます。まず売上高から変動費のみを引いた「限界利益＝売上高－変動費（＝固定費＋利益）」を求めます。
The technique analyzing the relationship among Cost, Volume, and Profit is called "CVP Analysis (Break-Even Analysis)." First, subtracting only variable costs from sales revenue gives the "Contribution Margin (Marginal Profit) = Sales － Variable Costs (= Fixed Costs + Profit)."
売上高に対する限界利益の割合が「限界利益率＝限界利益÷売上高＝1－変動費率（変動費÷売上高）」です。
The ratio of contribution margin to sales is the "Contribution Margin Ratio = Contribution Margin ÷ Sales = 1 － Variable Cost Ratio (Variable Costs ÷ Sales)."
利益がちょうどゼロ（売上高＝総費用、つまり限界利益＝固定費）となる売上高を「損益分岐点売上高」と呼び、「損益分岐点売上高＝固定費÷限界利益率＝固定費÷（1－変動費率）」で算出します。
The sales volume at which profit is exactly zero (Sales = Total Costs, meaning Contribution Margin = Fixed Costs) is called "Break-Even Sales," calculated as "Break-Even Sales = Fixed Costs ÷ Contribution Margin Ratio = Fixed Costs ÷ (1 － Variable Cost Ratio)."
また「目標利益を達成するための売上高」は「（固定費＋目標利益）÷限界利益率」となります。
Furthermore, "Sales Required to Achieve Target Profit" is calculated as "(Fixed Costs + Target Profit) ÷ Contribution Margin Ratio."
なお財務会計の「損益計算書（P/L）」では、①「売上総利益（粗利益）＝売上高－売上原価」、②本業の儲けである「営業利益＝売上総利益－販売費及び一般管理費」、③金融収支等を加減した「経常利益＝営業利益＋営業外収益－営業外費用」の順に計算します。
In financial accounting's "Income Statement (Profit & Loss Statement, P/L)," profit stages are calculated in order: ① "Gross Profit = Sales － Cost of Goods Sold," ② core business profit "Operating Profit = Gross Profit － Selling, General & Administrative Expenses (SG&A)," and ③ "Ordinary Profit = Operating Profit + Non-Operating Income － Non-Operating Expenses."
Key points
- 限界利益＝売上高－変動費／限界利益率＝限界利益÷売上高＝1－変動費率。
Contribution Margin = Sales － Variable Costs / Contribution Margin Ratio = Contribution Margin ÷ Sales = 1 － Variable Cost Ratio. - 損益分岐点売上高＝固定費÷限界利益率／目標利益達成売上高＝（固定費＋目標利益）÷限界利益率。
Break-Even Sales = Fixed Costs ÷ Contribution Margin Ratio / Target Profit Sales = (Fixed Costs + Target Profit) ÷ Contribution Margin Ratio. - 損益計算書：売上総利益＝売上高－売上原価／営業利益＝売上総利益－販管費／経常利益＝営業利益＋営業外収益－営業外費用。
Income Statement: Gross Profit = Sales － Cost of Sales / Operating Profit = Gross Profit － SG&A / Ordinary Profit = Operating Profit + Non-Operating Income － Non-Operating Expenses. - 【例】売上高5,000万円・変動費3,000万円・固定費1,200万円・目標利益400万円 → 限界利益＝5,000－3,000＝2,000万円（限界利益率＝2,000÷5,000＝40％）、損益分岐点売上高＝1,200÷0.4＝3,000万円、目標利益達成売上高＝（1,200＋400）÷0.4＝4,000万円
Example: Sales 50M yen, variable costs 30M yen, fixed costs 12M yen, target profit 4M yen → Marginal profit = 50 − 30 = 20M yen (marginal profit ratio = 20 ÷ 50 = 40%), Break-even sales = 12 ÷ 0.4 = 30M yen, Sales for target profit = (12 + 4) ÷ 0.4 = 40M yen - 【例】売上高4,000万円・売上原価2,500万円・販管費800万円・営業外収益50万円・営業外費用150万円 → 売上総利益＝4,000－2,500＝1,500万円、営業利益＝1,500－800＝700万円、経常利益＝700＋50－150＝600万円
Example: Sales 40M yen, COGS 25M yen, SG&A 8M yen, non-operating income 0.5M yen, non-operating expenses 1.5M yen → Gross profit = 40 − 25 = 15M yen, Operating profit = 15 − 8 = 7M yen, Ordinary profit = 7 + 0.5 − 1.5 = 6M yen
| Word | Meaning |
|---|---|
| 限界利益と限界利益率 | Contribution Margin (marginal profit) and Contribution Margin Ratio |
| 損益分岐点売上高（CVP分析） | Break-Even Sales (CVP Analysis) |
| 売上総利益・営業利益・経常利益 | Gross Profit, Operating Profit, and Ordinary Profit |
| 損益分岐点比率と安全余裕率 | Break-Even Point Ratio and Margin of Safety Ratio |
8. 原価企画の目標原価設定（割付法・積上げ法）とコストダウン手法（VA/VE）
8. Setting Target Cost in Target Costing (Subtraction vs. Addition Methods) and Cost Reduction (VA/VE)
新製品開発の「原価企画」において目標原価を設定する方法には3つあります。1つ目の「割付法（控除法）」は、市場で売れる予想販売価格から企業が確保したい目標利益を差し引いて「許容原価＝予想販売価格－目標利益」を求めるトップダウン方式です（市場競争力を反映できますが、技術的達成が厳しい場合があります）。
In "Target Costing (Genka Kikaku)" for new product development, there are three methods for setting target cost. First, the "Subtraction Method (Deductive / Market-Driven Method)" is a top-down approach that subtracts the company's target profit from the expected market selling price to find "Allowable Cost = Expected Selling Price － Target Profit" (reflects market competitiveness, though technical achievement can be challenging).
2つ目の「積上げ法（加算法）」は、現在の設計図面や製造技術をもとに各部品の材料費や加工費を下から積み上げて「成行原価（見積原価）」を求めるボトムアップ方式です（実現可能性は高いですが、市場価格を上回る恐れがあります）。
Second, the "Addition Method (Accumulation / Bottom-Up Method)" adds up material and processing costs for each part from the bottom up based on current design drawings and manufacturing technology to find "Drifting (Estimated) Cost" (highly feasible, but risks exceeding competitive market prices).
3つ目の「折衷法（統合法）」は、割付法の「許容原価」と積上げ法の「成行原価」のギャップを両面からすり合わせて目標原価を決定する実務的な方式です。
Third, the "Compromise (Integrated) Method" reconciles the gap between the subtraction method's "Allowable Cost" and the addition method's "Drifting Cost" from both sides to establish a practical target cost.
この目標原価を達成する強力なコストダウン手法が「VA（価値分析：既存製品対象）・VE（価値工学：開発設計段階対象）」です。製品の「価値（V）＝機能（F：果たすべき働き）÷コスト（C）」と定義し、不必要な過剰機能を削ったり、より安価な代替材料・構造で同じ機能を実現したりして価値Vを高めます。
A powerful cost-reduction methodology for achieving target cost is "VA (Value Analysis: for existing products) / VE (Value Engineering: for the design and development stage)." Defining product "Value (V) = Function (F: required performance/role) ÷ Cost (C)," VA/VE increases Value V by eliminating unnecessary excess functions or achieving the same function with cheaper alternative materials or structures.
Key points
- 割付法（控除法）＝「許容原価＝予想販売価格－目標利益」で求める市場志向のトップダウン方式。
Subtraction Method (Deductive Method) = market-driven top-down approach calculating "Allowable Cost = Expected Selling Price － Target Profit." - 積上げ法（加算法）＝現状の設計・製造技術から原価要素を積み上げて「成行原価」を求めるボトムアップ方式。
Addition Method (Accumulation Method) = bottom-up approach summing cost elements from current design and manufacturing capabilities to find "Drifting Cost." - VA/VE（価値分析・価値工学）＝「価値V＝機能F÷コストC」で捉え、必要な機能Fを維持・向上させながらコストCを低減する手法。
VA/VE (Value Analysis / Value Engineering) = defines "Value V = Function F ÷ Cost C," maintaining or improving necessary Function F while reducing Cost C. - 【例】予想販売価格3,000円・目標利益600円・成行原価2,650円 → 許容原価＝3,000－600＝2,400円（原価低減目標額＝2,650－2,400＝250円）
Example: Expected selling price 3,000 yen, target profit 600 yen, drifting cost 2,650 yen → Allowable cost = 3,000 − 600 = 2,400 yen (cost reduction target = 2,650 − 2,400 = 250 yen)
| Word | Meaning |
|---|---|
| 割付法（控除法・許容原価） | Subtraction Method (Deductive Method and Allowable Cost) |
| 積上げ法（加算法・成行原価） | Addition Method (Accumulation Method and Drifting / Estimated Cost) |
| 折衷法（統合法） | Compromise Method (Integrated Method) |
| VA（価値分析）とVE（価値工学：V＝F÷C） | VA (Value Analysis) and VE (Value Engineering: V = F ÷ C) |
試験によく出るポイントと覚え方
High-Frequency Exam Points and Memory Aids
原価管理は計算問題の宝庫です。①「製造原価＝製造直接費＋製造間接費」では、広告宣伝費や営業費（これらは販管費！）を製造原価に足さないこと、逆に外注加工費は「直接経費」として製造原価に入れることが鉄則です。
Cost Management is packed with calculation problems. ① In "Manufacturing Cost = Direct Manufacturing Cost + Manufacturing Overhead," never add advertising or sales expenses (those are SG&A!) into manufacturing cost; conversely, always include subcontract processing fees in manufacturing cost as a "Direct Expense."
②「補助部門費の直接配賦法」では、補助部門向けの数値を無視し、製造部門（第1製造・第2製造など）の比率だけで補助部門費を配分します。
② In the "Direct Allocation Method for Auxiliary Department Costs," ignore service figures provided to other auxiliary departments and allocate auxiliary costs using only the ratio between production departments (e.g., Production Dept 1 vs. Production Dept 2).
③「総合原価計算」では、加工費を按分するとき必ず「月末仕掛品換算量＝月末仕掛品数×加工進捗度」に変換してから完成品数と比例配分しましょう。
③ In "Process Costing," when apportioning conversion (processing) cost, always convert ending WIP into "Equivalent Units = Ending WIP Quantity × Degree of Completion (%)" before splitting proportionally with finished goods.
④「損益分岐点売上高＝固定費÷（1－変動費÷売上高）」と、⑤「材料費の価格差異・数量差異」の公式、さらに「割付法＝予想売価－目標利益（許容原価）」まで押さえれば満点が狙えます。
④ Mastering "Break-Even Sales = Fixed Costs ÷ (1 － Variable Costs ÷ Sales)," ⑤ the "Material Price and Quantity Variance" formulas, and "Subtraction Method = Expected Selling Price － Target Profit (Allowable Cost)" will set you up for a perfect score.
Key points
- 製造原価に「販管費（広告宣伝費・発送費・本社人件費）」は含めない！外注加工費は「直接経費（製造原価）」。
Never include "SG&A (advertising, shipping, head-office payroll)" in Manufacturing Cost! Subcontract processing fees are "Direct Expenses (part of Manufacturing Cost)." - 総合原価計算：始点投入の直接材料費は「そのままの数量比」、加工費は「進捗度を掛けた完成品換算量比」で按分する。
Process Costing: Direct materials input at the start are split by "raw physical quantity ratio"; Conversion costs are split by "Equivalent Units ratio (multiplied by % completion)." - 損益分岐点売上高＝固定費÷限界利益率／価格差異＝単価差×実際数量、数量差異＝数量差×標準単価。
Break-Even Sales = Fixed Costs ÷ Contribution Margin Ratio / Price Variance = Unit Price Diff × Actual Qty; Quantity Variance = Qty Diff × Standard Unit Price.
| Word | Meaning |
|---|---|
| 製造原価と総原価の区別 | distinguishing Manufacturing Cost from Total Cost |
| 補助部門費の直接配賦法 | Direct Allocation Method for auxiliary department costs |
| 完成品換算量による加工費按分 | apportioning conversion cost using Equivalent Units |
| 損益分岐点売上高と原価差異分析 | Break-Even Sales and Cost Variance Analysis |
Cost Management
Practice this chapter in the appOfficial references
- 中央職業能力開発協会（JAVADA） ビジネス・キャリア検定試験 3級 生産管理オペレーション 試験範囲 — https://www.javada.or.jp/jigyou/gino/business/subject.html
- 中央職業能力開発協会 編『ビジネス・キャリア検定試験 標準テキスト【専門知識】生産管理オペレーション 3級〔第4版〕』 — https://www.javada.or.jp/jigyou/gino/business/text.html