PURPOSE: To obtain an optimum illuminance irregularity state by obtaining a positional deviation of a light source by processing picture information to be fetched and driving a pulse motor based on the deviation to correct its position.

CONSTITUTION: Fig. (A) is an image when a position of a lamp 7 to a main optical axis and a focusing surface is optimum. This position is already grasped. Fig. (B) is an image when it is deviated in X-Y directions to the axis, and this distortion amount is already known. Fig. (C) is an image deviated to a focusing surface. The quantity of light becomes maximum at the optimum position. When an illuminance irregularity is desirably corrected in response to detected images corresponding to such positions of a light source, a picture processor 5 outputs X-Y driving amounts of the lamp 7 based on the deflected amount of the picture and a Z-driving amount based on the quantity of light, and a lamp driver 8 is operated to correct the position.