A retransmission control method has a physical control channel transmission step wherein a transmission side apparatus (10) transmits a new data specifier updated upon new packet transmission and a retransmission sequence number indicating whether transmission is the first transmission or retransmission, through a physical control channel related to a physical data channel. The retransmission control method also has a delivery confirmation information transmitting step wherein the receiving side apparatus (10) transmits delivery confirmation information to a packet received through the physical data channel, based on a new data specifier and the retransmission sequence number received through the physical control channel.