1. A pattern matching method which executes matching between the design data-based first image of an object sample, and a second image, characterized in that whether or not a periodic structure is included in a region to be subjected to the matching of said first image and second image is determined, so as to select a pattern, based on distance between an original point which is set in said image, and the pattern configuring said periodic structure, in the case where the periodic structure is included in said region, and to select a pattern based on coincidence of the pattern in said image, in the case where the periodic structure is not included in said region.