PURPOSE: To make a quick switching operation possible and to reduce the coupling loss by providing a light emitting element, a photodetecting element, and a through hole in the same enclosure and fixing an optical waveguide, which has the end faces of an optical axis parallel with optical axes of the light emitting element and the photodetecting element, to the through hole.

CONSTITUTION: A principal part consists of the photodetecting element 10, the through hole 14a, and a guide groove part 19 which guides a projecting part 1 projected into the enclosure 3 of a light incidence port 1. The light incidence port 1 is guided by the guide groove 19 and a light exit port 2 is guided by a guide groove 16 to move a movable body 5 between the first position and the second position. Consequently, the distance between the incidence end 6a of an optical waveguide 6 and the photodetecting element 10 and that between the exit end 6b of the optical waveguide 6 and a light emitting element 9 are shortened to make the movable body 5 small-sized, and the distance of movement of the movable body 5 is shortened. Thus, the switching operation is performed at the high speed.