Protection and safety device by which damage due to undesired exposure of photosensitive medium in a photocopying machine when the photocopying machine is switched off is prevented. A light blocking member is moved into the optical path for exposing the photosensitive medium when the light source and power source, respectively, for the copying machine are turned off and a cover portion for the machine is unlatched to prevent an undesired exposure of the medium and moved out of the optical path when the cover portion is latched and the light source and power source, respectively, are turned on to permit an exposure to take place.