A design pattern correcting method of correcting a design pattern in relation to a minute step of the design pattern, is disclosed, which comprises extracting at least one of two edges extended from a vertex of the design pattern, measuring a length of the extracted edge, determining whether or not the length of the measured edge is shorter than a predetermined value, extracting two vertexes connected to the extracted edge if it is determined that the length of the extracted edge is shorter than the predetermined value, and reshaping the design pattern to match positions of the two extracted vertexes with each other.