An ultrasound diagnostic apparatus adapted to measure the elastic modulus of a vascular wall includes a heartbeat selector for selecting a heartbeat in an M-mode image during the B/M-mode display and, after a heartbeat is selected, displays a B-mode image of a predetermined position in the selected heartbeat. The predetermined position is set in advance during the period of a heartbeat plus two additional periods before and after the heartbeat, with the length of each additional period being 20% on the length of the heartbeat. The ultrasound diagnostic apparatus as such allows the display of an appropriate B-mode image corresponding to the heartbeat to be analyzed.
