PROBLEM TO BE SOLVED : To provide a system which effectively provides the selling information and buying information (supply information) of a land, a building, etc., to real estate buyer and tenant (consumer side) and can further receive real estate selling information and perform real estate bidding consistently.SOLUTION : This system includes a control site for collecting and storing real estate information in a communication network such as the Internet, the terminal of a member who takes part in the real estate information, and a display changing means for switching the display of a real estate provider from the initial provider display provided and stored in the control site to the display of a particular key agent determined by the operation subject of the control site on data in providing real estate supply information corresponding to real estate demand information to be supplied to the control site and for providing the member terminal with combined information of the switched display of the key agent and the initial display of the real estate itself.