A method for manufacturing a semiconductor device, comprises forming a first film above a pattern forming material, patterning the first film to form a core material pattern, forming a second film above the pattern forming material so as to cover a side surface and an upper surface of the core material pattern, forming a third film above the second film as a protective material for the second film, etching the second and third films so that side wall sections including the second film and the third film are formed on both sides of the core material pattern and the second film and the third film of an area other than the side wall sections are removed, removing the core material pattern between the side wall sections, and transferring patterns corresponding to the side wall sections on the pattern forming material by using the side wall sections as a mask.