A branching device for a transmission path (84, 85) and a power supply path (81, 82) 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.