The present invention is to provide an ultrasound imaging apparatus which generates a scalar field image directly without obtaining a motion vector, so as to make tissue boundaries discernible. A received signal is processed to generate images of two or more frames, two frames are selected from the images, multiple regions of interest are set in one frame, and in the other frame, search regions each wider than the region of interest are set respectively for the multiple regions of interest. In the search region, multiple candidate regions each in a size corresponding to the region of interest are provided. Then, a norm is obtained between a pixel value of the region of interest and a pixel value of the candidate region, for each of the multiple candidate regions, thereby obtaining a norm distribution within the search region. An image is generated assuming a value representing the state of the norm distribution as a pixel value of the region of interest that is associated with the search region.
