A method of manufacturing a semiconductor includes performing exposure using a first photomask having a pattern line in which hole patterns and assist patterns not transferred onto the semiconductor substrate are arrayed at an equal pitch on the mask, the pitch being converted a first pitch Phole on the substrate when the mask patterns are transferred on the substrate, and performing exposure using a second photomask having a pattern line in which wiring patterns are arrayed at an equal pitch on the mask, the pitch being converted a second pitch Pline on the substrate when the mask patterns are transferred on the substrate, wherein m×Pline=n×Phole and m,n(m>n) are integers.