PURPOSE: To unitarily perform the monitoring control of an optical communication network and a radio communication network relating to a method and a device for managing a communication system composed of plural in-use lines and at least one standby line.

CONSTITUTION: The state information of the standby line 5 is transmitted to the in-use lines 1-4 in common. In the in-use lines 1-4, the transmitted state information of the standby line 5 and the monitoring information off its own lines are respectively entered in the DCCs of the section overheads of signals transmitted by its own lines and transmitted. In an external monitoring center, the monitoring information of the respective lines and the state information of the standby line 5 are taken out of the DCCs, the state information of the standby line 5 is managed as information belonging to the respective in-use lines, control information is transmitted to the respective lines based on the information and changeover control is respectively performed in the respective in-use lines.