PROBLEM TO BE SOLVED : reflecting the purchase of a purchaser of a real estate property. SOLUTION : buyers client device (11) from the real estate of purchase desired condition is inputted, a server device (10) . The condition (10) on the Internet server purchasers of corner (13). This is read by the seller (14, 15, 16) suitable for the conditions in a server device (10) of the real estate e-mail. Server device (10) of the buyer and seller in information box (17) from the real estate pm3ci information. In this way, the buyer purchases of desired unoccupied by the desired conditions on the Internet, the purchase of a purchaser of a real estate property suitable for a desired condition seller (14, 15, 16) can be widely invited from, the purchase of a purchaser of a real estate property suitable for the desired conditions, it is possible to provide to the buyer.