To protect the coupling surface of an optical waveguide cable from moisture and dirt.

When the optical waveguide cable is inserted into the bush 50, the bottom part 24 of an elastic cap 20 fitted in the light output side of the connector for the optical waveguide cable is pressed and broken by the cable. The elastic cap 20 functions as a gasket and a protection member. When the connector is inserted into the bush 50, the elastic cap 20 is held fitted in on the connector. During the inserting operation, the elastic cap 20 is stopped by a step part 54 in the reception hole 51 of the bush 50 and displayed by being pressed on the connector. At this time, the bottom part 24 is cleaved, so that the optical coupling surface of the cable is exposed.