Obtains the position of each of points composing the contour of a specific tissue shown in ultrasonic image data having been acquired at each time phase by pattern matching for each time phase. Obtains motion information of each of parts composing the specific tissue based on the position of each of the points composing the contour. For each time phase, obtain the differential value of the motion information of each of the parts by differentiating the motion information of each of the parts by time, and normalizes the differential value of the motion information. Assigns a color corresponding to the magnitude of the normalized differential value of the motion information to each of the parts displays an ultrasonic image at each time phase and furthermore display each of the parts of the specific tissue shown in the ultrasonic image of each time phase in the assign color.