Providing an inner wall image generation unit that generates, based on a three-dimensional image of a subject, an inner wall image representing the inner wall of a hollow organ of the subject, a specific region projection image generation unit that obtains a representative value based on a plurality of voxels on a light ray vector extending outside the hollow organ by a preset distance from each pixel of the inner wall image and generates a specific region projection image by projecting the representative value on the inner wall image, and a display control unit that superimposingly displays the specific region projection image on the inner wall image, wherein the specific region projection image generation unit sets some visualization target voxels from the voxels of the three-dimensional image, and obtains a representative value of a visualization target voxel in the plurality of voxels on the light ray vector.