In an optical field enhancement device in which localized plasmon is induced on a surface through illumination of excitation light and intensity of signal light emitted, by the illumination, from a sample placed on the surface is enhanced, forming sharp-edged petal-like fine uneven structures disposed at random on a substrate, and forming plate-like metal fine structures on tip portions of the sharp-edged petal-like fine uneven structures by depositing a metal from an oblique direction with respect to a direction perpendicular to a plane of the substrate on which the sharp-edged petal-like fine uneven structures are formed.