A first tomographic image of a three-dimensional image is displayed on a display screen, and a cursor to be operated by a user is also displayed in the displayed first tomographic image, and at least one second tomographic image intersecting the first tomographic image at a three-dimensional position in the three-dimensional image corresponding to a two-dimensional position pointed by the cursor in the first tomographic image is also displayed. A user input by a button operation giving an instruction to move the cursor is received. The cursor is moved to a two-dimensional position in one of the at least one second tomographic image corresponding to the three-dimensional position in the three-dimensional image corresponding to the two-dimensional position pointed by the cursor in the first tomographic image.
