To form UPS conforming to home appliance network standards.

A first injector 5 and a first wave detector 6 are installed at the input end for external systems of the UPS 1 connected with an interior distribution network, and further a second injector 7 and a second wave detector 8 are installed at the output end for the interior distribution network of the UPS 1 to build a home appliance network. Thus, an AC-to-DC converter 2 and a DC-to-AC inverter 3 comprising the UPS are controlled by a microcomputer 4. Further, a plurality of pieces of information on power and information on communication inputted to the microcomputer 4 through the second wave detector 8 and a band-pass filter 13 are processed at the microcomputer 4 and then sent out from the first injector 5 to an external system through a transducer 11 and an amplifier 10. In addition, a plurality of pieces of information on communication inputted to the microcomputer 4 through the first wave detector 6 and a band-pass filter 9 are processed at the microcomputer 4 and then sent out from the second injector 7 to the electrical household appliances and electrical equipment on the home appliance network through a transducer 12 and an amplifier 13.