An exposure unit for exposing a photosensitive image recording medium with light for forming an image corresponding to an original. The exposure unit comprises a light source; an original mounting table for mounting the original thereon, the original mounting table being disposed above the light source and extending over a light path zone so as to maintain the original at the light path zone, the photosensitive image recording medium being travelled over the original; contact means disposed above the photosensitive image recording medium for providing an intimate contact between the original and the photosensitive image recording medium when the original is brought into the light path zone for allowing a light to pass through the original and to reach to the photosensitive image recording medium; and, means for guiding travel of one of the original and the photosensitive image recording medium.