An image forming machine includes an exposure unit and a pressure development unit for forming an image on a microcapsule coated sheet. The exposure unit includes a plurality of light emitting elements, a substrate having reflective recesses formed in the surface thereof, the plurality of light emitting elements being disposed in the recesses, and a mask having openings formed opposite the plurality of light emitting elements. The reflective recess prevents light from the light emitting element from exiting through the pinhole other than the pinhole opposed to that light emitting element, thus improving the efficiency of utilization of exposure light. A partition may be provided between the light emitting elements.