An ultrasound diagnostic device that is able to generate images with high sensitivity for structures and unnoticeable artifacts. The ultrasound diagnosis apparatus includes an image-capturing part, a calculating part, and a composition part. The image-capturing part deflects ultrasound waves at a plurality of different deflection angles to transmit ultrasound waves to a subject, receives echo signals from the subject, and generates a plurality of ultrasound image data in which the deflection angles of the ultrasound waves are different in each. The calculating part obtains, based on the plurality of ultrasound image data, the trend of the angular dependence of the plurality of ultrasound image data on the deflection angles. The composition part changes the weights of the plurality of ultrasound image data in accordance with the trend of the angular dependence, and composes the plurality of ultrasound image data.
