An optical switch system used in a monitoring system for monitoring a large-scale optical transmission including a multiplicity of optical fibers, or like systems for switching optical transmission paths. The optical switch system comprises first and second optical switches. The first optical switch serves to optically connect one end face of a single first optical fiber selectively to one end face of any one of n second optical fibers. The second optical switch serves to optically connect end faces of n third optical fibers collectively and substantially synchronously to end faces of fourth optical fibers of a desired bundle selected from a plurality of optical fiber bundles each composed of substantially n optical fibers, the third optical fibers being optically connected at other end faces to other end faces of the second optical fibers.
