PURPOSE: To prevent a lens from being dislocated, extending over a long period of time, by pressing a condensing lens against a step difference part of a holder, by a screw ring which is screwed to an inside peripheral screw of the holder, and welding the screw ring to the holder.

CONSTITUTION: In one end part side of a holder 11, a lens fitting hole 12 is formed, and on the inside peripheral surface of the opening part side of the fitting hole 12, a screw 12a is formed. In the other end part side of the holder 11, a ferrule fitting hole 14 to which a ferrule 13 connected to an optical fiber is fitted is formed coaxially with the fitting hole 12. In a boundary part of the fitting holes 14 and 12, a step difference part 15 is formed. Into the fitting hole 14, a condensing lens 16 is inserted in a floating-fitted state, and the lens 16 is pressed against the step difference part 15 by a screw ring 17 which is screwed to the screw 12a. The screw ring 17 is welded to the holder 11. In this way, a dislocation of the lens 16 is prevented and its high reliability can be maintained extending over a long period of time.