In a Raman spectroscopy, the surface of metal film which is formed on a dielectric substrate in thickness of 50 to 200 nm and is characterized in that a plurality of fine holes satisfying the conditions defined by the following formulae are formed is caused to adsorb the material to be analyzed, light is projected onto the surface and the scattering light scattered by the surface is separated to obtain a spectrum of the scattering light,.lamda..times..times..times..times. ##EQU00001## d<.lamda.wherein .lamda. represents the wavelength of the projected light, a represents the cycle of the fine holes, d represents the diameter of the fine holes, .epsilon. 1 represents the dielectric constant of the metal film and .epsilon. 2 represents the dielectric constant of the medium around the surface of the metal film.