PURPOSE: To accurately correct irregular illumination at the time of variable power and to reduce light quantity loss by providing a mechanism whereby first and second light shielding members, which shield light beams from the periphery and central part of the picture, respectively, are advanced to and retreated from an optical path by the movement of an image forming lens.

CONSTITUTION: An irregular illumination correcting device is provided with the first light shielding member 26 capable of projecting into the optical path so as to shield a light beam from the periphery of the picture, the second light shielding member 27 capable of projecting into the optical path so as to shield a light beam from the central part of the picture, and the mechanisms 28 and 29 whereby the first and second light shielding members 26 and 27 are advanced to and retreated from the optical path by the movement of the image forming lens 7. Therefore, when the image forming lens 7 is moved to a reduction position, the illuminance of the periphery is raised; however, the first light shielding member 26 acts to correct the irregular illumination. On the other hand, the illuminance of the periphery is lowered at the time of enlargement; however, the second light shielding member 27 acts to correct the irregular illumination. Also, a part of light beams passing the image forming lens 7 is never shielded. This achieves accurate correction of irregular illumination at the time of variable power and the reduction of light quantity loss.