An ultrasonic imaging apparatus is provided, discriminates a noise area where echo signals are faint, by selecting a reference frame and a comparative frame from an image obtained by processing received signals and including a plurality of frames. A region of interest is set in the reference frame, a search area wider than the region of interest is set in the comparative frame, and multiple candidate regions being destination candidates of the region of interest are set within the search area. A degree of similarity between an image characteristic value in the region of interest and an image characteristic value in the candidate region is calculated, with respect to each of the candidate regions, to obtain a distribution of the degrees of similarity across the search area. Based on the similarity distribution, whether or not the region of interest corresponds to the noise area is determined.