PURPOSE: To prevent the copying by a copying machine regardless of the color of an image by providing a means which treats a document sheet with an ultraviolet-ray absorber by coating, impregnation, sticking, etc., and detects the ultraviolet-ray absorber according to the scanning exposure process of a copy document to make a response.

CONSTITUTION: The means which detects the presence of the ultraviolet-ray absorber (UV agent) incorporated in the document and stops copying operation or disables copy contents to be read is provided. When the copy contents are disabled to be read, the discharge of a charge transfer corotron, or exposure lamp is turned off. Then, the copying machine consists of an ultraviolet-ray emitting body 1 and an ultraviolet-ray detecting element 6 which are so arranged as to detect the UV agent incorporated in an original sheet 3 through platen glass 5. For the purpose, the UV agent is given to the document sheet by coating, impregnation, sticking, etc. Whether the UV agent is present on the surface of the document surface or not is discriminated before copying operation, and an original containing no UV agent is copied as usual.