An electronic commerce system and method for processing auxiliary order information in an on-line open market are provided. The system includes an on-line market server for brokering the on-line transaction on the Internet, wherein the on-line market server, when entrusted with partial or full processing of acquisition of auxiliary order documents for an object for sale requested for purchase from the buyer, acquires the auxiliary order documents from an issuing authority and requests the seller to deliver the object for sale, based on the auxiliary order documents; and at least one database for storing information related to the buyer and the seller.