A transmission apparatus includes a communication unit for performing transmission and reception of encoded data packets with other terminals, a redundant code generating unit for generating a redundant code packet for restoring data lost due to the loss of a data packet, a redundant code control unit for controlling the band used by the redundant code packet, a buffer for accumulating retransmission packets that can be retransmitted when corresponding data are lost, a retrieval unit for retrieving a corresponding retransmission packet from the buffer for retransmission upon receiving a retransmission request for the data packet, a retransmission control unit for controlling the band used for retransmission, and a band control unit for controlling the bandwidth of a redundant code based on the band used for retransmission and the band currently used for the redundant code.