Abstract: A reflection prevention film coats a backside of a stage glass by a vacuum evaporation and coating, etc. A light from a metal halide lamp is not reflected on the back of the stage glass by the reflection preventing film, and is transmitted through the stage glass and is reflected on a surface of the stage glass and a transparent manuscript. The light reflected on the surface of the stage glass and the transparent manuscript enters a projection lens unit and appears as a spot light on a screen, but because the light is not reflected on the backside of the stage glass, so that the amount of the light, which causes the spot light, can be reduced. As a result, the spot light on the screen is inconspicuous.