PURPOSE: An optical repeater system is provided to prevent communication errors by automatically converting an optical communication path into a bypassed optical communication line in errors. CONSTITUTION: A first optical splitter(165) separates a part of transmitted light from the transmitted light through a first division path. A second optical splitter(166) separates a part of the transmitted light from the transmitted light through a second division path. A first light detection apparatus(171) detects the light received through the first division path. A second light detection apparatus(172) detects the light received through the second division path. When light quantity received from the first and the second light detection apparatus is lower than the set reference level, a control unit(181) determines a malfunction in an optical path. The control unit controls a first and a second switch unit in order to convert a connected optical path into a non-connected optical path. [Reference numerals] (110) Donor unit; (130) Remote unit; (161) First optical switch; (162) Second optical switch; (165) First optical splitter; (166) Second optical splitter; (171) First light detection apparatus; (172) Second light detection apparatus; (181) Control unit; (183) Operation unit; (185) Display unit
