A power-line carrier communication apparatus comprising: a transmission unit; a reception unit; a power-line coupling unit for superimposing a signal derived from said transmission unit with respect to a power line as a power-line communication signal and also for extracting only a power-line communication signal from the power line; and a control unit for controlling respective structural elements of said transmission unit and of said reception unit, by which a communication operation is carried out by employing a plurality of sub-carriers; characterized in that said transmission unit includes a signal point mapping device for producing a plurality of bit streams from inputted transmission data so as to map said bit streams to signal points, corresponding to Pulse Amplitude Modulation signal points, of the respective sub-carriers, a wavelet inverse transforming device for modulating the respective sub-carriers by wavelet waveforms which are orthogonal to each other based upon signal point data of the respective sub-carriers mapped by said signal point mapping device so as to produce temporal waveform series data, and a D/A converter for converting the temporal waveform series data produced by said wavelet inverse transforming device into an analog temporal waveform series signal, and wherein said reception unit includes an A/D converter for digitally converting the power-line communication signal extracted from the power line by said power-line coupling circuit to obtain sampling-series waveform data, a wavelet transforming device for wavelet-transforming the sampling series waveform data obtained by said A/D converter into signal point data of the respective sub-carriers, and a symbol judging device for judging said bit streams mapped by said signal point mapping device by inverse-mapping a plurality of said signal point data outputted from said wavelet transforming device and for synthesizing the judged bit streams with each other as a reception data series; wherein said control unit is further arranged to output a selection signal for selecting a sub-carrier used to map/modulate data with respect to said signal point mapping device; and wherein said signal point mapping device is further arranged to map data with respect to the selected sub-carrier based upon said selection signal, and to map zero as to only real part data with respect to a sub-carrier which is not selected. a transmission unit; a reception unit; a power-line coupling unit for superimposing a signal derived from said transmission unit with respect to a power line as a power-line communication signal and also for extracting only a power-line communication signal from the power line; and a control unit for controlling respective structural elements of said transmission unit and of said reception unit, by which a communication operation is carried out by employing a plurality of sub-carriers; characterized in that said transmission unit includes a signal point mapping device for producing a plurality of bit streams from inputted transmission data so as to map said bit streams to signal points, corresponding to Pulse Amplitude Modulation signal points, of the respective sub-carriers, a wavelet inverse transforming device for modulating the respective sub-carriers by wavelet waveforms which are orthogonal to each other based upon signal point data of the respective sub-carriers mapped by said signal point mapping device so as to produce temporal waveform series data, and a D/A converter for converting the temporal waveform series data produced by said wavelet inverse transforming device into an analog temporal waveform series signal, and wherein said reception unit includes an A/D converter for digitally converting the power-line communication signal extracted from the power line by said power-line coupling circuit to obtain sampling-series waveform data, a wavelet transforming device for wavelet-transforming the sampling series waveform data obtained by said A/D converter into signal point data of the respective sub-carriers, and a symbol judging device for judging said bit streams mapped by said signal point mapping device by inverse-mapping a plurality of said signal point data outputted from said wavelet transforming device and for synthesizing the judged bit streams with each other as a reception data series; wherein said control unit is further arranged to output a selection signal for selecting a sub-carrier used to map/modulate data with respect to said signal point mapping device; and wherein said signal point mapping device is further arranged to map data with respect to the selected sub-carrier based upon said selection signal, and to map zero as to only real part data with respect to a sub-carrier which is not selected.