noun
A formal legal document that records the transfer of ownership of goods or property.
売約証書に署名して、取引は完了した。
The transaction was completed after signing the deed of sale.
売買契約書 is a broader sales contract, while 売約証書 specifically refers to a deed or bill of sale that finalizes the transfer.
Compound of 売約 (sale agreement) and 証書 (certificate, deed).