To process data according to a reception state of signals wirelessly transmitted to the main body of the system from an ultrasonic probe.

The main body 200 of the system judges whether image data acquired from the wireless signals are valid or invalid from the reception state of the wireless signals by a wireless reception part 204 is received. For example, it is judged whether the image data acquired from the wireless signals are valid or invalid from the received power of the wireless signals received by the wireless reception part 204. The main body 200 of the system stores the image data judged as valid into a data memory part 216 but does not store the image data judged as invalid into the data memory part 216.