1. An ultrasonic diagnostic apparatus comprising: a probe configured to ultrasonically scan a two-dimensional region or a three-dimensional region as a region to be scanned which includes at least part of a heart of an object and acquire ultrasonic data associated with the region to be scanned; motion vector processing circuitry configured to acquire temporal change curves of a wall motion parameter associated with a plurality of regions of the heart by using the ultrasonic data associated with the region to be scanned; wall motion parameter processing circuitry configured to acquire an index value associated with cardiac wall motion by calculating an absolute value of a difference of the wall motion parameter of two arbitrary regions, of the plurality of regions of the heart, at each phase in an analysis period by using temporal change curves associated with the two arbitrary regions, calculating a total sum of the absolute values in the analysis period, and normalizing the total sum with a predetermined value; and a display configured to display the index value in a predetermined form.