An ultrasonic diagnostic apparatus is provided with an ultrasonic probe, an ultrasonic image generating section, a head mounted display (HMD), and an orientation measurement section. The ultrasonic probe has two-dimensionally arranged ultrasonic transducers. The ultrasonic image generating section generates a 2D ultrasonic image representing a cross section of a three-dimensional area inside of a patients body. The HMD has an orientation sensor for outputting signals corresponding to motion of the HMD and a projector for projecting images and the like within the view of an operator Op. The orientation measurement section measures rotation direction and rotation angle of the operator Ops head (HMD). A plurality of cross sections of the three-dimensional area inside of the patients body for which the 2D image is generated is preliminary set, and the generated 2D ultrasonic image is switched according to the rotation direction and the rotation angle of the HMD.
