Provided is an ultrasonic diagnosis system in which a front-end (FE) device and a back-end (BE) device are set to a docking state, i.e., a wired connection state. While in this state, wired communication is used prior to wireless communication to exchange (pairing) key information (encryption keys, link keys) for performing exclusive wireless communication between the devices. The key information is stored in non-volatile memory in each device. After pairing, exclusive wireless communication is carried out between the devices using the key information each time that a separation state is formed.
