Provided is an ultrasound diagnostic device capable of improving the image quality of the region of interest and conserving electric power without limitation of the size of the region of interest. Even if a driving signal is supplied to the various transducers configuring the oscillator array at time (t1), the received signal processor remains OFF and does not turn ON. The received signal processor is only turned ON after the ultrasound echo signal from the region of interest starts being received at time (t4), in accordance with the measurement depth of the region of interest, and until reception of the ultrasound echo signal from the region of interest is completed at time (t5). Thereafter, the received signal processor reverts to the OFF state.
