A relay apparatus comprising: - a receiving unit (12, 14) that receives OFDM signals in which a plurality of channels are frequency multiplexed; - a FFT conversion unit that generates a plurality of sub-carrier signals by applying Fourier transform processing collectively to the OFDM signals received by the receiving unit (12, 14); - a first modification unit that modifies an arrangement of the plurality of sub-carrier signals generated by the FFT conversion unit while sub-carrier signals included in a channel are grouped into one unit; - a second modification unit that modifies an arrangement of the plurality of sub-carrier signals generated by the FFT conversion unit while sub-carrier signals included in a channel are grouped into one unit, - a first IFFT conversion unit that generates first new digital OFDM signals by applying inverse Fourier transform processing to the plurality of sub-carrier signals modified by the first modification unit; and - a second IFFT conversion unit that generates second new digital OFDM signals by applying inverse Fourier transform processing to the plurality of sub-carrier signals modified by the second modification unit; a frequency converter that performs frequency conversion on the OFDM signals from the second IFFT conversion unit, - a first D/A converter that converts the first digital signals to first analog signals, - a second D/A converter that converts the Frequency converted second digital signals to second analog signals, - a synthesis unit that synthesizes the first and the second analog signals to new analog OFDM signals, - a transmission unit (24, 26) that transmits the new analog OFDM signals generated by the synthesis unit, - wherein the band occupied by the arrangement prior to the modifications is a band with 8 channels, whereas the band occupied by the post modification arrangements is a band with 16 channels, - whereas 8 channels are to be used among the 16 channels, so that the number of channels included in the new analog OFDM signals is 8 channels. - a receiving unit (12, 14) that receives OFDM signals in which a plurality of channels are frequency multiplexed; - a FFT conversion unit that generates a plurality of sub-carrier signals by applying Fourier transform processing collectively to the OFDM signals received by the receiving unit (12, 14); - a first modification unit that modifies an arrangement of the plurality of sub-carrier signals generated by the FFT conversion unit while sub-carrier signals included in a channel are grouped into one unit; - a second modification unit that modifies an arrangement of the plurality of sub-carrier signals generated by the FFT conversion unit while sub-carrier signals included in a channel are grouped into one unit, - a first IFFT conversion unit that generates first new digital OFDM signals by applying inverse Fourier transform processing to the plurality of sub-carrier signals modified by the first modification unit; and - a second IFFT conversion unit that generates second new digital OFDM signals by applying inverse Fourier transform processing to the plurality of sub-carrier signals modified by the second modification unit; a frequency converter that performs frequency conversion on the OFDM signals from the second IFFT conversion unit, - a first D/A converter that converts the first digital signals to first analog signals, - a second D/A converter that converts the Frequency converted second digital signals to second analog signals, - a synthesis unit that synthesizes the first and the second analog signals to new analog OFDM signals, - a transmission unit (24, 26) that transmits the new analog OFDM signals generated by the synthesis unit, - wherein the band occupied by the arrangement prior to the modifications is a band with 8 channels, whereas the band occupied by the post modification arrangements is a band with 16 channels, - whereas 8 channels are to be used among the 16 channels, so that the number of channels included in the new analog OFDM signals is 8 channels.