PROBLEM TO BE SOLVED : To ensure the regional monopolistic business of a lease real estate agent.SOLUTION : The outline of lease real estate property and the information of each room is integrated into a data base so as to be displayable on the Internet, and one URL address corresponding to one property in the data base is displayed on the real state property with a signboard or plate or the like. This system is provided with a function of allowing a user to register a mail address for receiving a notice when any vacant room is available provided that the user is not able to find any vacant room at the time of performing access to the URL address of the lease real estate property, and the information is noticed to the destination of the registered mail address when the data base manager of the lease real estate property registers the vacant room.