Abstract: A confidential document reproduction prevention method of preventing confidential documents from being reproduced. This method is carried out by applying a particular material as a confidential mark at least to one portion of the surface of a confidential document, which material, when exposed to illumination light, is capable of emitting light with a wavelength different from the wavelength of the illumination light; detecting the light emitted from the material by a detector in a reproduction machine when the document is exposed to the illumination light; and making the reproduction machine inoperative, upon detection of the light emitted from the material.

Abstract: A photo-sensitive and heat-sensitive composition consisting essentially of a leuco-pigment; a hydrogen donator; a photo-reductant which, when exposed to a visible light, produces a reducing agent by the action of said hydrogen donator coexisting therewith; a photooxidant which, when exposed to an ultraviolet ray, causes said leuco-pigment coexisting therewith to generate color and simultaneously, when reacted with said reducing agent, is deprived of its own oxidizing ability; and a cobalt complex which reacts with the reducing agent in amplifying manner to thereby suppress the reaction of a color-forming system, and a recording element using the same.