PURPOSE: To obtain a copied picture image having high quality, by controlling the impressed voltage for destaticization to high → low → high at the absolute value thereof from the beginning to end period of irradiation of the projected light image of a picture image to a photoreceptor.

CONSTITUTION: The surface of a photoreceptor for which an n type semiconductor such as DdS is used is uniformly charged electrostatically to about -1,500V with a primary electrostatic charger 2, whereafter the dark part of the original is destaticized to about -150V over the entire surface by the simultaneous destaticization with a secondary electrostatic charger 3 of the polarity reversed from the polarity of the image exposure of the original and the primary charging. However, the potential in the destaticization stage on the surface of the photoreceptor in the ranges before and behind the image rises to a -50VW0V range and since this increased potential leads to the photographic fog in the stage of developing, the high voltage to be impressed to the destaticizer is changed to control the surface potential of the photoreceptor with respect to the dark part of the original after the secondary destaticization uniformly to -150V from the beginning to end period of the image exposure.