The present invention provides an ultrasonic diagnostic apparatus realizing improved visibility of a contour shape of signal components in an ultrasonic blood flow spectrum display image. The apparatus includes a gray-level correction unit for correcting intensity of an output result of a Doppler processing unit. The Doppler processing unit calculates a Doppler frequency shift in a reception signal output from a receiver and calculates blood flow velocity of a subject on the basis of the Doppler frequency shift. The gray-level correction unit has: a filtering unit for separating a signal and a noise from each other, which are included in a time-varying waveform of the blood flow velocity of the subject obtained by the Doppler processing unit on the basis of continuity on a space defined by the blood flow velocity and time; and a gray-level corrector for performing a gray level correction using, as a parameter, a boundary value between signal intensity and noise intensity obtained by the filtering unit.