PROBLEM TO BE SOLVED : To prevent real estate information from being enclosed by a real estate company to which a transaction relating to a real estate is entrusted by a real estate owner.SOLUTION : Real estate information includes transaction status information added to basic information relating to a real estate. The transaction status information is limited to information of maximum three types showing that a transaction partner of the transaction relating to a real estate is invited, a negotiation relating to the real estate is established between a client user who desires a transaction for the real estate and a real estate company, and/or a transaction contract for the real estate is concluded. When the transaction status information is changed, a real estate owner is notified that the status information is changed.SELECTED DRAWING : Figure 3COPYRIGHT : (C)2017, JPO&INPIT