Provided is an optical apparatus having high durability, less optical absorption than a hole-type metal thin film filter, high transmittance and high reflectance, and variable optical characteristics. The apparatus includes: a dielectric substrate; a metal structure group including multiple metal structures two-dimensionally and discretely disposed at regular intervals; and a dielectric layer covering the metal structure group, in which: the metal structures have a first length equal to or shorter than a predetermined wavelength in a visible light region in one direction, and a second length equal to or shorter than the wavelength in a perpendicular direction; and the metal structures resonates with light entering the dielectric substrate or the dielectric layer, having a variable dielectric constant, to generate localized surface plasmon resonance on a surface of the metal structures to have a minimum transmittance or a maximum reflectance of the light having the wavelength.