A three-dimensional ultrasonic diagnostic apparatus has a cross-sectional image generating unit, a region-of-interest setting unit, a three-dimensional image generating unit and a display unit. The cross-sectional image generating unit generates a cross-sectional image corresponding to a desired cross-sectional plane by performing a two-dimensionally scan on the cross-sectional plane within a three-dimensional scannable region. The region-of-interest setting unit sets a second region of interest for a three dimensional image within a three-dimensional region based upon a first region of interest in the cross-sectional image. The three-dimensional image generating unit performs a three-dimensionally scan on the three-dimensional region including the second region of interest, sets a view point based upon the second region of interest, and generates the three dimensional image, including the second region of interest, in a line of sight from the view point. The display unit displays the three-dimensional image.