The purpose of the present invention is to use multiresolution decomposition to reduce image sections, such as fogging and stationary artifacts, which appear in an ultrasound image. An image processing unit (20) performs resolution conversion processing on an ultrasound image obtained on the basis of a reception signal, to form a plurality of resolution images having mutually different resolutions, determines, on the basis of the plurality of resolution images, a reduction degree for each section in the image, and forms an ultrasound image in which reduction processing has been performed on each section in the image in accordance with the reduction degrees.
