A computer readable storage medium stores a facetization processing program that causes a computer to execute a process. The process includes: voxelizing a three-dimensional shape; generating first voxels corresponding to the three-dimensional shape; specifying an area surrounded by the generated first voxels; setting the specified area as voxels to generate second voxels; and facetizing third voxels at a boundary between at least one of the first voxels and a non-voxel area, and the second voxels and the non-voxel area.