A charging station performs communications by use of a superimposing/separating unit configured by connecting a capacitor, a coupling transformer and a capacitor to branch lines branching out respectively from a control cable and a grounded cable. An electric vehicle performs communications by use of a superimposing/separating unit configured by providing a coupling transformer to the control cable. A capacitor is also connected between the control cable and the grounded cable. Communications are allowed by the configuration of a closed loop circuit comprising the control cable, the branch line, the capacitor, a primary coil of the coupling transformer, the capacitor, the branch line, the grounded cable, the capacitor, and a primary coil of the coupling transformer.