To provide a technology to understand a reception status of signals transmitted in a wireless manner between an ultrasonic probe and the mainframe.

A received power detecting part 205 detects received power of the signal received by a wireless reception part 204. A received power display part for displaying the magnitude of the received power detected by the part 205 is installed on a receiver on the side of the main body of the apparatus or the like. The received power display part is constituted of, for example, a plurality of LEDs or the like and expresses the received power by the number of the plurality of LEDs which are illuminated.