A recording medium comprises a substrate and a recording layer overlaid on the substrate. The recording layer comprises a material, which has properties such that, when recording light having a predetermined wavelength λ1 is irradiated to the material, the material is capable of being caused to change into a fluorescent material and such that, when excitation light having a wavelength λ2 is then irradiated to the thus formed fluorescent material, the fluorescent material is capable of being caused to produce fluorescence. The wavelength λ1 of the recording light and the wavelength λ2 of the excitation light may be identical or different. The substrate may be constituted of a material having properties such that, when the excitation light is irradiated to the material, the material does not produce fluorescence having a wavelength identical with the wavelength of the fluorescence produced by the fluorescent material.