Article 509Duty of Party Receiving Offer to Contract to Give Notice of Acceptance or Refusal
第五百九条(契約の申込みを受けた者の諾否通知義務)
If a merchant receives an offer to contract that is in its line of business from a person with which it has regular dealings, the merchant must issue notice of its acceptance or refusal of the offer to contract without delay.
商人が平常取引をする者からその営業の部類に属する契約の申込みを受けたときは、遅滞なく、契約の申込みに対する諾否の通知を発しなければならない。
If a merchant neglects to issue a notice as referred to in the preceding paragraph, it is deemed to have accepted the offer to contract referred to in that paragraph.
merchant
「商人」
A person who, in their own name, carries on commercial transactions (商行為) as a business.
Defined inArticle 4, paragraph (1)· applies throughout the law