A branching device for a transmission path and a power supply path connecting a first trunk station and a second trunk station , the branching device comprising: a branching unit configured to be connected to a branch station by a transmission path and a power supply path , the branching unit comprises a switch, configured to switch a route by controlling the switch to switch the transmission path and the power supply path ; and a reconfigurable optical add/drop multiplexer, ROADM, device configured to be connected to the transmission path and the power supply path connecting the branch station and the branching unit , and which is further configured to supply, to the branching unit , a control signal for controlling the switch of the branching unit , wherein the branching device further comprises current detection means for detecting that there is no current flowing through a power supply path between the branch station and the branching unit , first optical signal detection means (56 1, , 61 1 ) for detecting an optical signal in the transmission path connecting the branch station and the branching unit , second optical signal detection means (56 2 , 61 2 ) for detecting an optical signal in the transmission path connecting the first trunk station and the second trunk station , and switching means for controlling the switch in such a way as to connect a transmission path between either of the first trunk station and the second trunk station , and the branch station , according to the detection results obtained by the second optical signal detection means (56 2 , 61 2 ), when the current detection means detects that there is no current flowing through a power supply path between the branch station and the branching unit , and the first optical signal detection means (56 1, , 61 1 ) detects an optical signal in a transmission path connecting the branch station and the branching unit. a branching unit configured to be connected to a branch station by a transmission path and a power supply path , the branching unit comprises a switch, configured to switch a route by controlling the switch to switch the transmission path and the power supply path ; and a reconfigurable optical add/drop multiplexer, ROADM, device configured to be connected to the transmission path and the power supply path connecting the branch station and the branching unit , and which is further configured to supply, to the branching unit , a control signal for controlling the switch of the branching unit , wherein the branching device further comprises current detection means for detecting that there is no current flowing through a power supply path between the branch station and the branching unit , first optical signal detection means (56 1, , 61 1 ) for detecting an optical signal in the transmission path connecting the branch station and the branching unit , second optical signal detection means (56 2 , 61 2 ) for detecting an optical signal in the transmission path connecting the first trunk station and the second trunk station , and switching means for controlling the switch in such a way as to connect a transmission path between either of the first trunk station and the second trunk station , and the branch station , according to the detection results obtained by the second optical signal detection means (56 2 , 61 2 ), when the current detection means detects that there is no current flowing through a power supply path between the branch station and the branching unit , and the first optical signal detection means (56 1, , 61 1 ) detects an optical signal in a transmission path connecting the branch station and the branching unit. <EOS>