An optical module is assembled using a main ring (16) and a reinforcing ring (18) to fasten associated parts when an optical fiber (8) fixedly inserted into a ferrule (10) is optically coupled to an optical device (12) provided in a housing (4). The point of fastening the main ring (16) with the reinforcing ring (18) is far outside the point of fastening the ferrule (10) with the main ring (16). By this configuration, the size of the optical module can be reduced while its mechanical strength can be increased. <IMAGE>
