To improve yield for increasing productivity by preventing a resist film from peeling off, when separating a photo mask from the resist film.

On a silicon substrate 11, photoresist or the like is used for providing a plurality of photomask support projections 14 and a resist film 15 for etching. Then, the photomask 16 is arranged on the resist film 15, while being supported by each photo mask support projection 14, and an exposure process is carried out, thus allowing the photomask 16 to come into contact with the resist film 15 with a small contact pressure at a site 11A for etching machining, preventing the resist film 15 from peeling off at the site 11A, when separating the photomask 16, and hence increasing the yield for improving productivity.