There is provided a light-emitting medium by which whether a valuable paper or the like is forged or not can be judged easily and promptly. A light-emitting medium constituting a valuable paper includes a light-emitting image. The light-emitting image is composed of a pattern area formed on a substrate by using a first fluorescent ink containing a first fluorescent material, and a background area formed on the substrate by using a second fluorescent ink containing a second fluorescent material. When UV-A is irradiated, the first fluorescent ink and the second fluorescent ink emit light of colors that are viewed as different colors from each other. In addition, when UV-C is irradiated, the first fluorescent ink and the second fluorescent ink emit light of colors that are viewed as different colors from each other, the colors being different from the colors that are viewed when the UV-A is irradiated.