Two electrode wires longitudinally provided along the inner surface of an elastic insulating member having a hollow portion are exposed from said elastic insulating member, the resistive element comprising a resistor body and the resistive element's lead wires is formed into a U-letter shape, said two electrode wires exposed from said elastic insulating member and said resistive element's lead wires are electrically connected via one metal plate, and a portion wherein one of said two electrode wires and one of the lead wires extending from both ends of said resistor body are electrically connected and a portion wherein the other one of said two electrode wires and the other one of the lead wires extending from both ends of said resistor body are electrically connected are separated by cutting said one metal plate.