The present invention has a cash register 1 and a Bluetooth portable terminal 2 which conduct short-range wireless communication to each other. The cash register 1 decreases transmission power during periods when a search request processing and a connection request processing for the Bluetooth portable terminal 2 are conducted, thereby being connected with only a prescribed Bluetooth portable terminal 2. At the time of providing services, electric power for transmission is increased. Therefore, it is possible to surely connect with the prescribed Bluetooth portable terminal 2. After connected with the prescribed Bluetooth portable terminal, even if the Bluetooth portable terminal 2 moves at comparatively broad range, it is possible to provide the Bluetooth portable terminal 2 with services.