PURPOSE: To accurately control an exposure operation by a method wherein a residual light counter, with which the residual light is accurately and quantitatively measured, is provided, the residual light is measured by a computer used for control, and the correction of the residual light is added to exposure amount data which is different for every product lot.

CONSTITUTION: A residual light amount counter 16 counts the counter pulse 14 in proportion to the level of illumination from the point of time at which a shutter 2 started a closing movement. The amount of residual light is measured in advance by a controlling computer 7 before an article is exposed, and the new data of exposing amount, which is obtained by deducting the amount of residual light from the exposing-amount data to be set for every article, is set on a counter 8. As a result, the entire amount of exposure, including the amount of residual light, can be controlled. Also, the amount of residual light is measured every time the shutter 2 is moved, the result is compared with the last and the past data of measurement, a judgement is given, a motor is properly controlled, and as a result, a highly precise exposing amount control can be conducted.