PROBLEM TO BE SOLVED : To solve problems wherein a tenant is really recruited and what a vacant room actually is, etc., cannot be learned unless directly asking on the telephone although signboards such as ' Now leasing' and ' Vacant room available' , are constantly hung up on a real estate property for rent.SOLUTION : A data base created by making the summary of the real estate property for rent and information about each room is made into the form displayable on the Internet. In URL address is displayed on the real estate property by a signboard or a plate, etc. The summary of real estate information and states of vacancy of each room is made confirmable from a portable terminal, etc., such as a cellular telephone by using the Internet from the spot. When no vacancy is available in the real estate property, a function for registering a mail address is provided and vacancy is informed to the registered mail address at a point in time when a manager registers the vacancy. A user can register vacancy information from a data that the outer appearance, current state, etc., of the real estate property for rent are confirmed.