PURPOSE: To make it possible to copy only the surface of an original distinctly even if characters, etc., are written in the rear surface of the original by arranging an optical means for diffusing and transmitting light beam in the position this side of a supporting body in an exposure means.

CONSTITUTION: The light transmissible original 3 is closely arranged on a photosensitive pressure sensitive paper 4 and an irradiation light from a lamp 1 is transmitted in order of the supporting body 3a of the original 3 and the coloring part of the original 3. And a diffusion plate 6 which diffuses the light beam is arranged between the original 3 and a filter 2. The light beam emitted from the lamp 1 becomes only light of a prescribed color by passing a color separation filter 2 and radiated to the diffusion and transmission plate 6. The light beam projected to the diffusion and transmission plate 6 becomes the light beam diffused on the original side to radiate the rear surface of the color original. Even if the coloring part which shades the light beam exists on the rear surface of the original, the light beam reaches the surface of the original by by-passing the coloring part owing to the light diffusion by the diffusion plate 6. Thus, only surface of the original can be distinctly copied even if the characters, etc., are written in the rear surface of the original.