Abstract: A baseboard for retaining a photosensitive plate thereon is fixedly disposed immediately below an exposure light source and in a path provided by means for feeding the plate to the baseboard and means in alignment with the feeding means for delivering the plate from the baseboard after exposure. A frame for superposing a negative film and a stiff transparent sheet on the photosensitive plate fed to the fixed baseboard is provided with squeegee rolls which are rollable on the transparent sheet to press out and remove air from between the film and the plate. With frame moved upward and downward relative to the fixed baseboard, the apparatus performs the successive steps of feeding the plate, removing the air, exposing the plate and discharging the exposed plate.