In contact-printing the image of a transmission type original on a photosensitive plate material positioned on a printing stage, the original is in advance fixed to a transparent sheet which is movable between an open position and a closed position. The original is fixed to the transparent sheet at a predetermined position thereon at which the original will be registered with the plate material when the transparent sheet is moved to its closed position. In the open position, the transparent sheet is held away from the printing stage to permit change of the plate material and in the closed position, the transparent sheet sealingly covers the plate material in a predetermined positional relationship therewith and the space under the transparent sheet is evacuated to bring the transparent sheet, the original and the plate material into close contact with each other. Then, the three members are exposed to light.