A transmitter station and receiver station have common maximum number of transmission bits per symbol of each subcarrier and information of encoding types to be selected. The transmitter station selects the modulation type from the propagation path quality of each subcarrier, executes encoding with the encoding type corresponding to the number of bits for communication with the selected modulation type, distributes the maximum number of transmission bits per symbol of each subcarrier by dividing the code, and transmits the data through modulation of only the number of bits for communication with the selected modulation type among distributed bits in each subcarrier. The receiver station executes demodulation by selecting the modulation type used for demodulation from the propagation path quality, summarizes the demodulation result with addition of reception of the signal having a zero degree of likeliness for the number of wanted bits, and executes decoding to the result of demodulation.