When subject tissue such as a living body is a viscoelastic body, a shear wave propagation velocity is changed according to the frequency of a shear wave. An ultrasonic diagnostic apparatus applies a displacement generating transmission beam from an ultrasound probe (1) based on a signal from a displacement generating unit (10) to generate a shear wave, applies a pulse wave to the biological tissue by a displacement detecting unit (30), detects the particle velocity of the shear wave, estimates a viscosity parameter from a temporal extent of a waveform of the particle velocity of the shear wave detected at a viscoelasticity analyzing unit (34), and displays the estimated viscoelasticity on a display unit (7).
