An ultrasonic imaging apparatus is provided, which is capable of discriminating a noise area where echo signals are faint. The ultrasonic imaging apparatus selects a reference frame and a comparative frame from an image made up of two or more frames, the image being obtained by processing received signals. A region of interest is set in the reference frame, and a search area wider than the region of interest is set in the comparative frame, multiple candidate regions being destination candidates of the region of interest are set within the search area, a degree of similarity of an image characteristic value between in the region of interest and in the candidate region is calculated, with respect to each of the candidate regions, so as to obtain a distribution of the degrees of similarity across the search area. With this configuration, based on the similarity distribution, it is possible to determine whether or not the region of interest corresponds to the noise area. By way of example, it is configured such that statistics is obtained, which compares a minimum value of the degree of similarity with an overall value thereof in the similarity distribution. By comparing the statistics with a threshold value, it is possible to determine confidence of the region of interest.
