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 ; bringing the photomask into contact with the photoresist film ; and exposing the photoresist film to light having a wavelength that is longer than the wavelength 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 .