An ultrasonic image diagnostic device includes: an ultrasonic transmitting/receiving unit which repeatedly transmits an ultrasonic wave to a subject and receives an ultrasonic echo from the subject; an image processor which generates a plurality of ultrasonic images illustrating an in-vivo state of the subject based on ultrasonic echoes sequentially received from the subject; and a motion evaluating unit which performs motion evaluation of a moving body in the plurality of generated ultrasonic images, wherein the motion evaluating unit includes an interval setting unit which sets an interval between the ultrasonic images which should be compared with each other for the motion evaluation so as to be variable in increments of the number of frames based on a frame rate of the plurality of generated ultrasonic images.