Many kinds of rubber parts such as fusing roller, media handling roller, and cleaning blade apply to commercial electrophotographic copiers and printers. Recently, charging roller, developing roller, and toner transfer roller or belt composed of rubber materials have progressed remarkably. The cause of this progress is that electric resistance of rubber materials can be precisely controlled in semi-conductive region such. as 106-1012Ωcm. Charging roller is used for providing charge to a photoconductor. The photoconductor is charged by micro space charging, i.e. directly contacting the DC or DC plus AC voltage applied semi-conductive rubber roller on the photoconductor. In a developing process using a non-magnetic one-component developer, charged toner particles are transferred from the developing rubber roller to the photoconductor by the latent image potential. In a transfer process, toner image created by a developing process is transferred to a recording paper by the transfer electric field generated between the voltage applied transfer roller and the photoconductor or the intermediate transfer drum/belt. This report focuses on applications of semi-conductive rubber for electrophotographic system, and explains the electrical and mechanical properties of semi-conductive rubbers in demand and the conditions for using in electrophotographic processes.