To provide an ultrasonic diagnostic apparatus for automatically optimizing a display system.

The apparatus includes a data density adjuster 42 for adjusting the density of echo data. When a user adjusts the data density, the data density adjuster 42 outputs the signal of a data density value to a transmitting/receiving part 30, a driving part 24, and a display mode selecting part 46. When the data density value is inputted, the display mode selection part 46 calculates a frame rate based on the exchange depth of an ultrasonic wave, and the number of beams, and compares the frame rate (Hz) with a prescribed threshold n(Hz). When the frame rate is smaller than the prescribed threshold n, a selection signal to select a line unit display mode is outputted to a display control part 28. When the frame rate is larger than the prescribed threshold, a selection signal to select a frame unit display mode is outputted to the display control part 28.