An inspection system includes a detection device arranged between a connector that couples a plurality of optical fibers to a port and the port; and a determination device that determines whether there is dart between the connector and the port, based on an output from the detection device, wherein the detection device includes a plurality of diodes that convert light that is output from each of the plurality of optical fibers to an electrical signal indicating intensity and distribution of the light, and the determination device includes a processor configured to determine whether there is dart between the connector and the port, based on the intensity and distribution of the light, which are indicated by the electrical signal.