To provide an efficient support method for specified item transaction capable of saving the time and labor for long-term negotiations between the person in charge of a branch center and a client as much as possible.

This method for supporting the negotiations for a specified item transaction comprises a Web site disclosure step by a Web site 7 of performing this transaction support service; a step 21 of requesting a member registration on the Web site 7; a member registration step 22; a step 23 of opening a page exclusive for client; a step 24 of storing the item inquiry by the client in a collation DB; a step 25 of transmitting a collation notice mail to each branch center 10 performing an item processing; a step 26 of determining the person in charge by each branch center 10; a step 27 of advancing the negotiation through the writing to the page exclusive for client by the person in charge and the client and storing the negotiation history in a negotiation history database; and a contract step 28 of performing a contract procedure after establishment.