1. An ultrasonic diagnostic apparatus comprising: a section image constituting unit which transmits ultrasonic into an object and produces a section image of the object based on a received signal and a two-dimensional elasticity image constituting unit which processes the signal to produce a two-dimensional elasticity image of an elasticity value representing elasticity; a rendering unit which produces volume data formed of a plurality of the two-dimensional elasticity images and selects and renders elasticity value data of the volume data included in a desired elasticity value range to produce a three-dimensional elasticity image of the elasticity value data in the elasticity value range; and a display unit which displays the three-dimensional elasticity image and at least one of the two-dimensional elasticity image and the section image showing an area corresponding to the elasticity value range.