The DFT 12 converts a modulated digital signal into a spectrum of a frequency band. A use frequency band notification unit in a reception device notifies a transmission device 1 of a use frequency band. A deletion unit 141 in the transmission device 1 deletes a spectrum of a band other than the use frequency band after shaping of a spectrum waveform based on the water filling principal by a shaping unit 13. Then, a digital signal for each data series concerning the spectrum obtained after deletion by the deletion unit 141 is synthesized by a synthesizing unit 16 and sent from the transmission device 1 to the reception device. A reception side conversion unit in the reception device converts the digital signal sent by the transmission unit into a spectrum of a frequency band. A turbo equalization unit performs turbo equalization on the converted spectrum.