1. An ultrasonic diagnostic apparatus comprising: a multi-resolution decomposition unit which performs a multi-resolution decomposition on ultrasonic image data so as to obtain first image data corresponding to a low-band signal component and at least one of second image data corresponding to a high-band signal component; a reduction process unit which performs a regional maximum value reduction process of reducing a regional maximum value lower than a first level and a regional minimum value reduction process of reducing a regional minimum value higher than a second level on the first image data and the at least one of the second image data; and a reconstruction unit which performs a multi-resolution reconstruction by using the first image data and the at least one of the second image data having been subjected to the regional maximum value reduction process and the regional minimum value reduction process so as to create a reconstruction image.