A transmission device comprises first interfaces each of which receives time-division multiplexed signals from an external device in units of frames, a switch which is connected with the first interfaces and sets paths of the signals received from the first interface in regard to each packet, and second interfaces each of which is connected with the switch, receives the signals from the first interface via the switch, and transmits the received signals to a different transmission device in units of packets. The first interface selects signals having the same destination from the signals contained in the received frame and stores the selected signals having the same destination in one packet.