Optical access system and monitoring method

An optical access system that performs communication using an optical signals on which management control signals used for management and control are superimposed in a plurality of transmission lines connecting a plurality of subscriber devices, the optical access system comprising:

• a plurality of splitters that are provided for the respective transmission lines and split a plurality of optical signals transmitted from the plurality of subscriber devices;
• a monitor configured to acquire the management control signal from each of the plurality of optical signals split by each of the plurality of splitters;
• and
• an output device that is provided between the monitor and the plurality of splitters and outputs the plurality of optical signals split by the plurality of splitters to the monitor,
• wherein the monitor includes a plurality of receivers configured to convert each of the plurality of optical signals output from the output device into electrical signal, and a plurality of management control signal separators that acquire the management control signal from the electrical signal.