To provide a cross section display program and a cross section display device capable of alleviating a processing load for determining the shape of a cross section, thereby drawing a cross section at high speed.

A rectangular solid approximation conversion part 120 makes a solid approximate a solid of a combination of multiple rectangular solids. An intersection point calculation part 150 calculates an intersection point of a ridge of each of the rectangular solids making up the approximated solid with a cross section acquired by a cross section information acquisition part 140. A solid drawing part 160 carries out the processing of drawing a cross section of each rectangular solid from the coordinate of the intersection point calculated by the intersection point calculation part 150 for all the rectangular solids, and draws the cross section of the solid by piecing together those cross sections. In this way, the program can alleviate a processing load for determining the shape of a cross section, and draw the cross section at high speed by first executing the processing by the rectangular solid approximation conversion part 120.