Examples of the binder resin used in combination with the above-mentioned electroconductive particles for preparation of the electroconductive support 11 include thermoplastic resins, thermosetting resins and photosetting resins such as polystyrene, styrene--acrylonitrile copolymer, styrene--butadiene copolymer, styrene--maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride--vi