To solve a problem of a conventional optical repeater that a monitor control function in a sub circuit section whose command demodulation section is faulty does not normally function at all even when its arithmetic processing section itself is normally in operation if a fault takes place in only the command demodulation section in a monitor control section in the one sub circuit section.

The optical repeater of this invention is provided with: sub circuit sections each comprising an optical amplifier for amplifying an optical signal transmitted on an optical transmission line, a command reception section for receiving a command signal through the optical transmission line, and a monitor control section for monitoring/controlling the optical amplifier according to the command signal; and a signal connection section that transmits/receives signals between the plurality of monitor control sections and provides a command signal to the one sub circuit section via the other sub circuit section on the occurrence of a fault in the command reception section of the one sub circuit section.