Ultrasound diagnostic device and image evaluation display method

Provided is a medical image panorama forming (compositing) technology, with which a dependency on a user's proficiency is small, and with which a composite image is generated which is useful in a diagnosis. When compositing a superposition image and generating a composite image, information used in the compositing is used in evaluating the reliability of the superposition image. The result of the evaluation is presented to a user. The information used in the evaluation is a degree of movement of the superposition image with respect to a superpositioned image. It would also be permissible to present the evaluation result to the user being reflected in the composite image. Specifically, provided is an ultrasound diagnostic device, comprising: an image compositing unit which composites a superposition image upon a superpositioned image and generates a composite image; a display device which displays the composite image; a movement degree computation unit which computes a frame movement degree which is a movement degree of the superposition image with respect to the superpositioned image; and an evaluation unit which evaluates the reliability of the superposition image on the basis of the frame movement degree. It would further be permissible for the display device to display the result of the evaluation by the evaluation unit.