1. A pattern matching method for matching between a design data-based first image of an object sample, and a second image, comprising steps of: determining whether or not a periodic structure is included in a region to be subjected to the matching of said first image and second image; selecting a pattern, based on a distance between an original point which is set in said images, and pattern configuring said periodic structure, in the case where the periodic structure is included in said region; and selecting a pattern based on coincidence of the pattern in said images, in the case where the periodic structure is not included in said region.