PURPOSE: To obtain a good transferred image without transfer voids at the time of high humidity and to permit the complete sepn. of a transfer material even at the time of low humidity by specifying the position of a pointed electrode and the shape of insulators on both sides thereof.

CONSTITUTION: A separating means of an image forming device is provided with the pointed electrode 7 which maintains a prescribed spacing A on the down stream side of a transfer corona discharger 5 with respect to the moving direction of the transferred image, projects toward a photosensitive body side and positions the tip thereof at the prescribed spacing B maintained from the surface of the photosensitive body, the insulators 6 which sandwich the electrode 7 from both sides and have a radial aperture toward the photosensitive body side from the root part thereof and a power supply part 8 which impresses the voltage of the polarity reverse from the polarity of the transfer corona discharger and lower than a self-discharge start voltage to the pointed electrode. Both the distance of the pointed electrode from the photosensitive body and the distance thereof from the transfer corona discharger are maintained at prescribed distances. The balance in the optimum state of the sepn. effect and transfer performance is thereby maintained.