An optical repeating system includes an optical transmitter and an optical amplifying repeater. The optical transmitter transmits a supervisory command and a control command to the optical amplifying repeater as a first sub-signal. The supervisory command is a command to supervise internal circuits of the optical amplifying repeater, and the control command is a command to control the optical amplifying repeater. The optical amplifying repeater includes multiple sub-modules each for amplifying and repeating main signals on multiple sets of optical transmission lines. When receiving the supervisory command via the optical transmission line, each sub-module transmits a supervisory signal indicating the supervisory result associated with the supervisory command to an optical receiver as a second sub-signal. In addition, when receiving a predetermined control command via the optical transmission line, each sub-module initializes another sub-module of the multiple sub-modules in response to the predetermined control command. The optical amplifying repeater can restart its control program even when it has fallen into a state where it is difficult to continue to execute the normal operation in accordance with the control program because of some exception or the like.