A mounting method for mounting an electroconductive sheet on a developer seal member for sealing a developer discharging opening provided in a developer accommodating container for accommodating a developer. The electroconductive sheet is provided with an adhesive material on one surface thereof. A separation sheet is adhered to the one surface, wherein the separation sheet is larger than the electroconductive sheet. The method includes a suction step of contacting a suction tool to the other surface of the electroconductive sheet. The suction tool is effective to suck air to attract the electroconductive sheet thereon. An exposure step separates the separation sheet from the electroconductive sheet, while the electroconductive sheet is being sucked by the attraction tool, so that the one surface of the electroconductive sheet is exposed. A bonding step, after performing the exposure step, binds the one surface of the electroconductive sheet to the developer seal member, while the electroconductive sheet is being sucked by the suction tool.