The invention provides a power−line carrier communication apparatus including a transmission unit with a signal point mapping device for mapping a plurality of bit streams produced from transmission data, a wavelet inverse transforming device for modulating the respective sub−carriers by wavelet waveforms which are orthogonal to each other for producing temporal waveform series data, and a D/A converter for converting the temporal waveform series data into an analog temporal waveform series signal; and a reception unit with an A/D converter for obtaining sampling­series waveform data from a power−line communication signal, a wavelet transforming device for wavelet−transforming the sampling−series waveform data into signal point data of the respective sub−carriers, and a symbol judging device for judging bit streams mapped by the signal point mapping device by inverse−mapping a plurality of these signal point data, and for synthesizing the judged bit streams with each other as a reception data series.
