PURPOSE: To prevent recording paper from coming into contact with a discharge electrode without providing a screen or the like on the opening of the discharging electrode, by rendering flexible the side plate of the casing of the discharge electrode in the upstream side in the direction of the rotation of a photoreceptor.

CONSTITUTION: An image transferred recording paper P is separated from the surface of the photoreceptor Z with a separating device S, and fed to a conveyor T. Similar-structured corona dischargers are used for a transfer device O and the separating device S, etc. Even when the forward end of the paper P happens to touch the flexible side plate part 2a of the casing 2 as an unusual case, or the end happens to intrude into the openig of the casing 2, the part 2a is pressed by the end or the side of the paper P and bent as shown in the alternate long and 2 short dash line in the figure, and it can prevent th direct contact of the paper P with the discharge electrode 1. Accordingly, damage of the electrode 1 or burning of the paper P, or the like trouble can be avoided.