An image processing device 100 divides a hollow organ 50 extracted from a volume image 40 using a plurality of planes 20 including an arbitrary eye vector 23 or a plurality of planes along the centerline of the hollow organ 50, transforms the coordinates of a point inside the hollow organ 50 along a predetermined convex surface set outside the hollow organ 50 on each plane 20, and gives a pixel value of an original position to a corresponding point after the coordinate transformation. Then, a folded volume image is generated by combining the respective planes 20 in a reverse procedure of the division procedure, and a shaded folded three-dimensional image 90 is generated by projecting the folded volume image to a projection surface from the arbitrary viewing direction and is displayed on a display device 107.
