PROBLEM TO BE SOLVED : To enable a person who desires to sell real estate and a person who desires to buy to set the trading price of the real estate without trouble, and to enable the person who desires to buy to obtain information on the real estate without large trouble.SOLUTION : A selling-side terminal 380 and a buying-side terminal 390 are connected to a host computer 180 through a communication network 400. Then when the person who desires to sell the real estate inputs information on the real estate to be sold through the terminal 380, the host computer 180 receives the information and stores it in an item data storage part 600. Then the host computer 180 computes an auction price of the real estate and sends the information on the real estate to the buying-side terminal 390 together with the auction price. The person who desires to buy bids for the desirable real estate through the buying-side terminal 390 and that is sent to the selling-side terminal 380.