Image data of the interior of a sample (S) are sequentially created on the basis of reception signals at the time when ultrasonic waves are transmitted into the sample (S) so as to scan the interior thereof, movements of respective control points set on the image data are tracked so as to evaluate temporal changes of velocities of motions of the sample (S), and differences of timings of the motions in the sample (S) are color-displayed on the basis of the temporal changes of the velocities.
