Provided is an optical relay system (10) which is capable of suppressing wasteful power consumption of an entire system to a low level. The optical relay system (10) includes a plurality of relay devices (30) and a network control device (20). The network control device (20) causes an optical signal to be regenerated by a regenerative repeater (35) within the relay device (30) existing at an upstream of the relay device (30) reporting that the optical signal has deteriorated by a degree exceeding a predetermined level. Further, the network control device (20) causes the regenerative repeater (35) to stop regenerating the signal in a case where deterioration of the signal remains within an allowable range even when the regenerative repeater (35) stops regenerating the signal.