Substantially improves the efficiency of operation and maintenance management of optical fiber lines. The warning light is lit on the monitor terminal upon detection of failure, such as increased loss, fiber break, and water invasion in closure. Indicates the failure location on an electronic map and notifies the maintenance staff by means of e-mail or telephone.The test system speeds up identification of failure location and facilitates restoration. Enables the maintenance center during cable installation to test the installed equipment as a remote manual test.Performs automatic testing of multiple fibers at once, thus saving installation labor and reducing the required work period. Conducts periodic automatic testing of optical fiber lines for preventive maintenance, or quality maintenance.