Ultrasonograph

To provide a small-size ultrasonic diagnostic apparatus manufactured at a low cost, which is capable of displaying an optimum image in both the B mode and the color-Doppler mode, without providing a plurality of drive amplifiers of different transmission voltages to each transmission channel. The ultrasonic diagnostic apparatus has multiple display modes. The ultrasonic diagnostic apparatus includes: a probe for transmitting an ultrasonic beam and receiving a reflection wave of the ultrasonic beam reflected from a tissue of a biological body; a low-pass filter for filtering the reflection wave; and an image processing section for performing on the filtered reflection wave an image process corresponding to a selected display mode. The probe transmits an ultrasonic beam which has an amplitude determined according to the selected display mode. The low-pass filter has such a filter characteristic that at least the cutoff frequency varies according to the selected display mode.