A relay apparatus (5-1, 5-2, 5a, 5b) comprising: a first control section (23a, 23b) which connects to a first network; a second control section (24a, 24b) which connects to a second network, the type of which is different from that of the first network; a third control section (21a, 21b) which connects to a third network (1, 3), the type of which is the same as the first network; and a relay section (22a, 22b) which relays a signal from the first control section or the second control section to the third control section, selects a path from the first network and the second network to be operated as an active system, further referred as ACT system, and performs path switching based on information regarding the first network and information regarding the second network, wherein the second control section converts a transmission unit for transmission in the first network into a transmission unit for transmission in the second network, and transmits the transmission unit to the second network, the relay section receives information indicating a degree of a failure of the first network as information regarding the first network from the first control section, receives information indicating a degree of a failure of the second network as information regarding the second network from the second control section, selects a path having a lower degree of a failure as the ACT system based on the received information, and performs path switching, the first network is a time-division multiplexing, TDM, network including a plurality of TDM communication apparatuses in which the TDM communication apparatuses transmit and receive a TDM signal as the transmission unit, and the second network is a packet network including a plurality of packet communication apparatuses in which the packet communication apparatuses transmit and receive a packet as the transmission unit, and the second control section converts a TDM signal into a packet and transmits the packet to the packet network. a first control section (23a, 23b) which connects to a first network; a second control section (24a, 24b) which connects to a second network, the type of which is different from that of the first network; a third control section (21a, 21b) which connects to a third network (1, 3), the type of which is the same as the first network; and a relay section (22a, 22b) which relays a signal from the first control section or the second control section to the third control section, selects a path from the first network and the second network to be operated as an active system, further referred as ACT system, and performs path switching based on information regarding the first network and information regarding the second network, wherein the second control section converts a transmission unit for transmission in the first network into a transmission unit for transmission in the second network, and transmits the transmission unit to the second network, the relay section receives information indicating a degree of a failure of the first network as information regarding the first network from the first control section, receives information indicating a degree of a failure of the second network as information regarding the second network from the second control section, selects a path having a lower degree of a failure as the ACT system based on the received information, and performs path switching, the first network is a time-division multiplexing, TDM, network including a plurality of TDM communication apparatuses in which the TDM communication apparatuses transmit and receive a TDM signal as the transmission unit, and the second network is a packet network including a plurality of packet communication apparatuses in which the packet communication apparatuses transmit and receive a packet as the transmission unit, and the second control section converts a TDM signal into a packet and transmits the packet to the packet network.