【AI千本ノック法律相談 #079 】 物価波に　定価の契り　夏軋む

弁護士吉川淳：
今日は、インフレ進行下の「固定価格契約と価格改定交渉」のご相談です。総務省統計局の2026年5月の全国消費者物価指数は、総合指数113.5で前年同月比1.5％上昇でした。また、2025年度の最低賃金は1,121円で、引上げ額66円は過去最大です。物価と賃金が同時に上がる局面では、受注企業にとって「契約どおりに履行すると赤字だが、勝手に値上げもできない」という板挟みが非常に起きやすくなります。そこで、契約書の価格改定条項、協議の進め方、価格転嫁をめぐる公的指針（ガイドライン）、そして将来契約の設計が重要になります。
Today’s consultation concerns fixed-price service contracts during inflation. According to Japan’s Statistics Bureau, the nationwide CPI for May 2026 showed an all-items index of 113.5, up 1.5% year on year. In addition, the nationwide weighted average minimum wage for FY2025 rose to 1,121 yen, with a 66-yen increase—the largest on record. In such an environment, service providers often face a classic squeeze: performing exactly as promised leads to losses, yet they still cannot unilaterally raise their contract price. This is why, in practice, the wording of price-adjustment clauses, the documentation of negotiations, official pass-through guidance, and future contract design become central legal issues.

人間の弁護士吉川淳：
「原則として難しいです。契約は当事者の合意で成立し、その内容もまずは合意に従って決まるのが基本ですから、契約書に物価スライド条項や賃金上昇時の具体的な改定条項がない以上、受注者が請求書だけ書き換えて一方的に単価を上げることは通常できません。勝手に増額請求し、相手が従わないからといって直ちに履行を止めると、こちらが債務不履行だと主張される法的リスクがあります。
もっとも、『何もできない』という意味ではありません。現在の契約については、まず契約文言を精査して、協議条項、仕様変更条項、中途解約条項、不可抗力条項、再委託・人員配置条項がどうなっているかを確認すべきです。そして、物価・賃金・採用コストの上昇が、受注時に予定していた採算構造をどう崩したかを数値で整理し、正式な改定申入書を出して、協議の記録を残すことが重要です。法律上の原則は合意（現行契約の内容）ですが、ポイントは『後で見ても交渉要請が合理的だったと示せるか』にあります。」
“As a general rule, that is very difficult. Contracts are formed by agreement, and their contents are also determined primarily by that agreement. So unless the contract already contains a price-slide clause or a wage-escalation adjustment clause, the service provider ordinarily cannot just rewrite its invoice and raise the price unilaterally. If you impose a higher charge on your own and then suspend performance when the client refuses, you risk being accused of non-performance yourself.
That said, this does not mean you are powerless. For the current contract, you should first review the exact wording carefully—especially any consultation clause, change-of-scope clause, mid-term termination clause, force majeure clause, and staffing or subcontracting clause. Then quantify how inflation, wage increases, and hiring costs have changed the economic assumptions of the deal, submit a formal request for revision, and preserve the negotiation trail. The legal starting point is agreement, but in practice the real battle is whether you can later show that your request for renegotiation was objectively reasonable.”

人間の弁護士吉川淳：
「取引類型によって差がありますが、少なくとも『発注側は何も協議しなくてよい』という時代ではありません。公正取引委員会の労務費転嫁指針は、発注者側に対し、労務費上昇分の価格転嫁に向けて誠実に交渉し、受注者に過大な立証負担をかけず、価格交渉を理由に不利益な取扱いをしないことを求めています。中小企業庁も、3月と9月を価格交渉促進月間とし、交渉や転嫁の実態を調査し、状況の悪い親事業者には指導・助言を行う運用をしています。
したがって、御社の取引が取適法や関連する中小受託取引の規律（労務費転嫁指針等）に乗る可能性があるなら、単なる『お願い』ではなく、公的ルールに沿った交渉要請として組み立てるべきです。具体的には、①いつ、誰に、どの根拠資料を示して、②どういう増額案を出し、③相手がどう答えたかを文書で残すことです。相手が“ゼロ回答”を続けるほど、後で行政相談・申告・法的対応を考える際の材料が整います。逆に、感情的に『ではもうやりません』と先に言ってしまうと、こちらが不利になります。」
“This depends somewhat on the legal category of the transaction, but at the very least, we are no longer in an era where the ordering party can simply refuse to engage at all. The JFTC’s labor-cost pass-through guidance calls on buyers to negotiate in good faith over labor-cost increases, avoid placing excessive evidentiary burdens on suppliers, and refrain from retaliatory treatment because a supplier requested a price review. The SME Agency also promotes regular price negotiations in March and September and conducts follow-up surveys, with administrative guidance for poorly performing parent companies.
So if your transaction may fall within subcontract-related regulation or other fair-trading frameworks for smaller suppliers, your approach should not be framed as a mere favor request; it should be structured as a formal negotiation request aligned with public rules. In practical terms, you should document: (1) when and to whom you made the request, and with what supporting materials, (2) what revised price proposal you presented, and (3) how the other side responded. The more the client keeps giving a flat refusal, the more material you build for later administrative consultation, reporting, or legal action. By contrast, if you emotionally say ‘then we quit’ too early, that can weaken your own position.”

人間の弁護士吉川淳：
「自己判断で進めるのは危険です。まず、仕様書に書かれた頻度や人員水準を、発注者の承認なく落とすのは原則として避けるべきです。『採算が合わないから掃除回数を減らす』『受付時間を短くする』というのは、契約上の債務の内容をこちらの都合で変更する行為に見えやすく、損害賠償や契約解除の口実を相手に与えます。
中途解約についても、契約書に任意解約権、一定期間前の通知解約、著しい事情変更時の協議条項、継続困難時の解除条項があればそこを使いますが、単に『赤字だからもうやめたい』だけで当然に抜けられるわけではありません。日本法では、事情変更による契約修正や解消は例外的な扱いです。ですので現実的には、①現契約では正式な改定協議と仕様調整協議を並行し、②どうしても維持不能なら契約条項に即した解約ルートを探し、③将来契約ではCPI、最低賃金、燃料費、資材費などを指標にした定期見直し条項、一定幅を超えた場合の再協議条項、合意不成立時の終了条項まで入れておく、という三段構えが重要です。」
“That is also dangerous to handle by self-help alone. First, you should generally avoid reducing the service frequency or staffing level stated in the specifications without the client’s approval. Saying, for example, ‘we will reduce cleaning rounds’ or ‘shorten reception hours’ because the contract has become unprofitable can easily be characterized as a unilateral alteration of your contractual obligations, giving the client grounds to claim damages or terminate.
As for mid-term termination, you must begin with the contract text: if there is a voluntary termination clause, a notice-based termination right, a hardship consultation clause, or a termination clause for continuation becoming impossible, those provisions become central. But Japanese practice does not ordinarily allow a party to walk away simply because the contract has become loss-making. Contract adjustment or dissolution based on changed circumstances is exceptional. So the realistic approach is a three-step one: (1) pursue formal price-renegotiation and scope-adjustment talks under the current contract, (2) if continuation truly becomes impossible, identify a lawful exit route under the agreement itself, and (3) for future contracts, include regular review clauses tied to CPI, minimum wage, fuel costs, and material costs, together with re-negotiation triggers and an exit mechanism if agreement cannot be reached.”