Polarities of voltages on a plurality of electric wires are reversed with an H-bridge circuit applied in accordance with control information or data to be transmitted, information or data transmitted as change of polarities is found on the reception side, and the transmitted power is restored to direct current power through a bridge diode circuit and is used as power supplied to a load. Each load has a unique ID input and storage means, and the present invention is a communication method in which the unique ID is designated to the transmitted information or IDs are designated to groups to control a load. In addition, it is a method for spreading a PWM operation time to minimize noise generated in accordance with PWM driving on the reception side. In a direct current transmission and reception environment, data or a command signal for power demand response is mapped with the polarity of voltage and is transmitted to each customer, and it may be applied to the power demand response technique.