Disclosed is a process for producing a photoresist pattern, comprising the steps of: preparing a photomask that comprises a metal nano structure having a metal film arranged thereon and can generate a plasmon resonance, on a mask substrate; preparing a photoresist film that is formed on the surface of the resist substrate and is sensible to light having a wavelength (X); bringing the photomask into contact with the photoresist film; and exposing the photoresist film to light having a wavelength (Y) that is longer than the wavelength (X) and is shorter than the peak wavelength of a plasmon resonance band of the metal nano structure, thereby transferring a pattern of the metal film in the photomask onto the photoresist film.