To easily obtain the position and shape of a subject and the positional relation of a sample volume.

This ultrasonic diagnostic apparatus includes: sound line data obtaining means 1 to 3; image data preparation means 4 to 7; an image composition means 8 for composing the image data from the image data preparation means; a display means 10, which displays the image data as a reference image or a diagnostic image; an input medium 11 by which an operator can input an operating command; and a sample volume setting mean 9 to set the sample volume. The image composition means makes the display means display a CF mode image as the reference image, and the diagnostic image of a position designated by the sample volume is displayed on the display means. The apparatus is provided with: an operation supervision means 9 to detect whether predetermined operation is performed until a time preceding the present time by a prescribed period; and a control means which makes the image composition means prepare image data of a special mode in stead of preparation of the image data of the CF mode image when the operation supervision means detects that the predetermined operation is performed.