Abstract: [Problem(s)] It is an object of the present invention to provide a polygon processing apparatus that deletes information on a polygon which is not used in drawing, without changing the shape of a necessary polygon. [Means for Solving Problem(s)] The present invention generates a plurality of scanning lines from polygons and determines or not whether all the scanning lines are shielded by another polygon. Then, the polygon whose all the scanning lines are shielded are assumed to be a polygon which is surrounded by another polygon and is not to be drawn, and drawing processing is not executed for the polygon. The present invention is based on a knowledge that those polygons which are not used in drawing can be excluded from those to be drawn with simple processing, without changing the shape of a necessary polygon.