PROBLEM TO BE SOLVED : To easily sign lease of real estate in real time by using map information of a homepage on which the map information is displayed.SOLUTION : A server 1 to provide the homepage on which the map information is displayed on the Internet admits insertion of advertisement from a client 2 of an authorized lease recruiter 2A to an applicable position where a real estate rental property exists in the map information and is constituted of a process (step A) to insert the advertisement to the applicable position where the rental property exists in the map information displayed on the homepage by accessing the server 1 from the client 2 of the lease recruiter 2A, a process (step B) to browse the advertisement of the rental property in the map information by accessing the homepage from a client 3 of a lease applicant 3A, a process (step C) to conclude the rental agreement of the rental property between the applicant 3A and the recruiter 2A of the rental property and a process (step D) to pay a rate such as rental fee to be required for lease from the lease applicant 3A to the lease recruiter 2A.