PURPOSE: To simplify the adjustment of a charger for holding the surface potential of a photosensitive element at a prescribed value by forming a drum-like photosensitive element having a pressing member for pressing the OPC terminal part of a supporting column by a conductive element and electrical insulation between a pressing member and the supporting column.

CONSTITUTION: The inside of a cylindrical supporting column 1 is provided with an OPC winding shaft 2 and an OPC delivery shaft 3. A belt-like photosensitive element OPC delivered from the OPC delivery shaft 3 is wound around the peripheral surface of the supporting column 1 from a opening part 4 of the supporting column 1 and, after one cycle, the OPC is led again into the inside of the supporting column 1 through the opening part 4 and wound around an OPC winding shaft 2. The space between the conductive pressing member 5 and the supporting column 1 is electrically insulated and the status is applied also to the OPC. An electrical insulating member is fixed to a part contacting with the OPC of the pressing member 5 or the supporting column 1 by adhesion or the like.