A densification processing unit (20) densifies image data composed of a plurality of pieces of line data corresponding to a plurality of ultrasound beams obtained by scanning with an ultrasonic beam (a transmission beam and a reception beam). The densification processing unit (20) densifies the image data by compensating for density of scanning direction data arranged at a low density along the scanning direction of the ultrasonic beam on the basis of depth direction data arranged at a high density along the depth direction of the ultrasonic beam within the imaging data.
