A PC (1) comprises a tomographic image information acquisition section (6), a memory (9), a volume rendering calculator (13), a display unit (2), a mouse (4), and a voxel label setting section (18). The tomographic image information acquisition section (6) acquires tomographic image information. The memory (9) stores voxel information about the tomographic image information. The volume rendering calculator (13) samples voxel information in a direction perpendicular to the line of sight, on the basis of the voxel information. The display unit (2) displays calculation results from the volume rendering calculator (13). The mouse (4) inputs cutting instructions for a liver (22) displayed on the display unit (2). The voxel label setting section (18) displays the status of the liver (22) after cutting using the cutting instructions from the mouse (4), and displays blood vessels (23) inside the liver (22) included in a cut portion (C), in a pre-cut state even after cutting.
