A highly sensitive ultrasonic diagnostic apparatus is provided by improving the signal to noise ratio of the receiving system.The ultrasonic diagnostic apparatus comprises an ultrasonic probe 10, which transmits and receives ultrasound to and from a subject, a transmitting unit 20, which supplies driving signals to the ultrasonic probe, and a receiving unit 60, which processes signals to be outputted from the ultrasonic probe 10 and calculates diagnostic information regarding the subject. The ultrasonic probe 10 is equipped with a receiving probe (transducer) 10B, the receiving sensitivity of which changes according to the level of bias voltage to be applied. The receiving unit 60 is equipped with a modulated bias amplification unit 24, which applies signals of bias voltage with modulated amplitude to the receiving probe (transducer) 10B. By this, a certain demodulation processing (for example phasing processing or Doppler demodulation) can be applied to ultrasonic reflection signals at the receiving process of the receiving transducer.
