PURPOSE: To prevent sticking of dust or the like to extend the life of a screen, by erasing a primary electrostatic latent image immediately after the end of the retention copy in the method where the electrostatic field on a screen photoreceptor is used to modulate an ion current and an image is formed.

CONSTITUTION: A screen 1 (a conductive member 2, a photoconductive layer 3, and an insulating layer 4 are provided) charged electrostatically primarily by a corona discharger 5 is subjected to irradiation of an image and electrostatic charge due to an image exposure corona discharger 8 simultaneously and exposed throughout with a uniform light 9, and the ion current of a modulating corona discharger 15 is controlled by a primary electrostatic latent image formed on the screen 1 to form a secondary latent image on a recording paper 16, and this image is developed to attain a picture. When this process is terminated, a corona discharger 24 for erasing the primary latent image is used to charge electrostatically the insulating layer 4 to a potential approximately equal to the potential of the dark part of the primary electrostatic latent image, thus erasing the primary electrostatic latent image.