A terminal includes a transmitting and receiving unit transmitting and receiving an observation packet for observing the transmission quality and data, and a transmission quality managing unit (i) exchanging the observation packet with another terminal via the transmitting and receiving unit, (ii) observing a loss rate of the data between the terminal and the other terminal and writing to the observation packet the degraded state information indicating the loss rate in the case where the terminal receives the data, and (iii) subtracting the congested state information from the degraded state information included in the observation packet collected from the other terminal in order to calculate a transmission error rate of the data in the terminal and the relay device in the case where the terminal transmits the data. An error correction code processing unit determines a forward error correction capability based on the transmission error rate calculated by the transmission quality managing unit and assigns to the data to be transmitted the forward error correction code according to the forward error correction capability.