1. An ultrasonic diagnostic apparatus comprising: a selection unit which is configured to select at least one of past images acquired in the past from an image storage management unit in the ultrasonic diagnostic apparatus, an image recording medium connected to the apparatus, and an image storage management system connected via a network; a reference image registration unit which is configured to register a selected image in an image list for image reference together with information about a storage location of the image; an acquisition unit which acquires the image registered in the image list on the basis of the information about the storage location and stores the image in an image storage management unit in the ultrasonic diagnostic apparatus; and a display unit which arbitrarily repeatedly displays the acquired past image in the reference list as a reference image side by side with a live image, wherein the display unit executes image processing to the reference image based on image processing to the live image, and wherein the display unit executes the image processing in which at least one of a luminance and dynamic range of the reference image is adjusted so as to correspond to the live image.