An ultrasound diagnostic apparatus comprises: a diagnosis judging unit that judges whether diagnosis using an ultrasound image generated by an image producer is in progress and a control unit that controls a transmission actuator and reception signal processors to select a high image quality mode for operation where transmission and reception of ultrasonic waves from a given number or more of oscillators of an oscillator array are performed in a whole area of the ultrasound image when the diagnosis judging unit determines that diagnosis is in progress and controls the transmission actuator and the reception signal processors to select a power saving mode for operation where transmission and reception of ultrasonic waves from at least a part of the given number or more of the oscillators of the oscillator array are stopped according to a region of the ultrasound image when the diagnosis judging unit determines that diagnosis is not in progress.
