An identification device of the present invention determines authenticity of an article with an anti-counterfeiting medium varying in a pattern of observed light depending on changes in light characteristics of radiated light, using the anti-counterfeiting medium. The identification device includes a similarity calculation unit that determines the degrees of similarity between a plurality of captured image data of the anti-counterfeiting medium obtained with differences in the light characteristics of the radiated light and reference image data corresponding to the light characteristics; and an authenticity determination unit that determines whether the degrees of similarity determined for the individual light characteristics exceed thresholds set corresponding to the individual light characteristics to make an authenticity determination on whether the anti-counterfeiting medium is genuine.