In the case of transmitting a signal of at least three bits in one symbol, when receiving a retransmission request signal from a radio station of a communication partner, a transmission apparatus 10A retransmits only the bits (lower bits) that are susceptible to error, without retransmitting the bits (higher bits) that are not readily susceptible to error and that are obtained by processing in a modulation section 11. A reception apparatus 10B of the communication partner performs error correction processing using the bits (higher bits) and that are stored in memories 16 and 17 and that are not readily susceptible to error, and the bits that are obtained by retransmission and that are susceptible to error (lower bits).