On a film as an object of processing, a first positive photo-resist having a dense hole pattern is formed. On the first positive photo-resist, a second positive photo-resist is formed to fill each of the plurality of holes of the pattern. To the second photo-resist, an image of dark points as a bright-dark inverted image of a high-transmittance half-tone phase shift mask is projected and exposed. By the development of second photo-resist, a pattern of dots of the second photo-resist formed at portions of the dark point image are left in any of the plurality of holes of the pattern. The film as the object of processing is patterned, using the first and second photo-resists as a mask.