PURPOSE: To execute satisfactory electric discharge, even if a member to be electrified is a photosensitive body, by providing an air hole connected to a space between a dielectric and the surface of the member to be electrified on the dielectric.

CONSTITUTION: An air hole 20 penetrating in the vicinity of electrodes 11, 12 is pierced on a dielectric 10. This air hole 20 communicates with an air chamber 23 formed by holding the dielectric 10 in a stepped part 3b by a holding material 3. A tube attaching port 3c is provided, on a part of the holding material 3, and a suction tube 22 is attached thereto. That is, as for the suction tube 22, its one port is fitted to a suction pump, and the other is fitted into the holding member 3 through the tube attaching port 3c, and this tube has a function for leading the air sucked from the air hole 20, to the suction pump. In such a way, NNOx, and ozone does not remain on the surface of a photosensitive body 2, and there is no possibility that characteristics of the photosensitive body are varied.