According to an embodiment, a manufacturing method of a semiconductor device includes forming, on a film to be processed, a plurality of first core material patterns and a plurality of second core material patterns. Each of the second core material patterns is drawn from an end portion of the corresponding first core material pattern. The manufacturing method includes forming an opening pattern having one or a plurality of openings in the second core material pattern so that a first distance and a second distance are less than a predetermined distance. The first distance is a distance between an edge of the second core material pattern at a side of an adjacent first core material pattern and the opening pattern. The second distance is a distance between an edge of the second core material pattern at a side of an adjacent second core material pattern and the opening pattern.