In the present invention, a wave transmission/reception unit is provided in the distal end of a probe. The wave transmission/reception unit includes a 2D-array oscillator, an electronic circuit, and a relay substrate for electrically joining the 2D-array oscillator and the electronic circuit. The face of the wave transmission/reception unit on a subject side thereof is a wave transmission/reception face. A temperature detection unit is provided to the relay substrate. In the present invention, a surface temperature estimation unit estimates the temperature of the surface of the wave transmission/reception face on the basis of the detected temperature from the temperature detection unit and the power consumption by the wave transmission/reception unit. Specifically, by separately taking into account the power consumption of the electronic circuit and the power consumption of the 2D-array oscillator, the temperature difference from a temperature detection location to the surface of the wave transmission/reception face is estimated, and the surface temperature is estimated from the detected temperature and the temperature difference.
