A packet transmission apparatus is provided. The packet transmission apparatus transmits a packet having a limited arrival deadline through a best-effort network. The packet transmission apparatus includes an automatic packet retransmission section to control retransmission of an undelivered packet, a forward error correction coding section to add a redundant packet to a data packet block, and a redundancy determining section to dynamically determine redundancy of the redundant packet based on observed network state information, so that a loss rate after error correction at a receiver achieved by only the retransmission of the undelivered packet satisfies an allowable loss rate after error correction.