PURPOSE: To easily obtain the sectional image of an area concerned without missing the said area by providing a storage device, a first display means, a curved line designating means, and a second display means specified respectively.

CONSTITUTION: A section of cutting crosswise along the backbone is determined by a sagittal image. First of all, a curved line axis in a backbone direction is set on the sagittal image on a display screen by a moving axis determination circuit 112. The determination of the coordinate on the curved line may be executed by inputting all coordinate points by an input device 105 such as a track ball. The curved line determined in this way is written in a graphic memory 108, and is displayed on the display screen by a full line of a broken line, etc. Next, an objective image pickup section is determined on the basis of this curved line axis. At that time, a straight line to show the image pickup section is operated so as to be displayed always by the angle in a normal direction to the curved line axis by a normal direction determination circuit 113. Besides, the section moves on the curved line axis in accordance with input from the input device 105 such as the track ball. Accordingly, the backbone on the area concerned is never missed.