In a radio-communication system and a radio station, one or more subcarriers are grouped, and the maximum bit number per symbol of the modulation method used for each subcarrier is determined for each group and shared between a transmitting station and a receiving station. The transmitting station divides and allocates a coded signal to subcarriers in accordance with the bit number per symbol, modulates each of the allocated signals by a predetermined modulation method, and transmits the modulated signals. The receiving station demodulates the received signal by the predetermined modulation method, adds a signal having zero likelihood when the bit number per symbol of a modulation method for demodulation is different from a maximum bit number, and decodes the demodulated signal by summarizing the demodulated results.