1. A pattern image comparison method, comprising: a first input step of inputting a first pattern image based on design data for a reticle mask or a semiconductor device; a second input step of inputting a second pattern image of said reticle mask or semiconductor device manufactured based on said design data; a calculation step of calculating at least one parameter of parameters including a part or all of area, outer periphery, barycenter, and diagonal line of said first pattern image and said second pattern image; and an output step of outputting a result of comparison of a pattern on said reticle mask or semiconductor device and a pattern of said design data based on said calculated parameters of said first and second pattern images.