When a two-dimensional tomogram is to be displayed, motion information associated with a direction orthogonal to the tomogram is colored and mapped on the tomogram to be visualized by using the volume data of a TSI image. For example, a mapping image is generated by color-mapping shortening information at each point on a cardiac tissue on a short axis view by using the volume data of the TSI image. Superimposing and displaying the mapping image on the original short axis view makes it possible to simultaneously observe the shortening information even while a short axis view is obtained and observed.