PROBLEM TO BE SOLVED : To provide a useful data base system for registering and managing real estates to be supplied and to be required especially concerning a storehouse and a land to be used. SOLUTION : Concerning information on existent real estates to be supplied and information on real estates for potential demand, the data base system is constructed on the Internet for a site manager to accept registration both from a member by collecting a membership fee and from a non-member by not collecting a membership fee, and corresponding to a browsing request to the relevant data base system, basic real estate information securing the anonymity of a person, who registers the real estate, is provided to the non-member but the real estate information of the retrieved result securing the anonymity of a person, who registers the relevant real estate, is provided to the member by selecting the real estate registering person more precisely than the non-member. Besides, a method for getting contact with these real estate information registering persons is provided while securing anonymity by means of selection.