To obtain a high polarized wave extinction rate after the projection light of a laser diode pass through a polarization plane maintaining type optical fiber without deteriorating the polarized wave extinction rate of the projection light by obtaining a structure which hardly applies stress due to mechanical local fixation to the polarization plane maintaining type optical fiber.

After a ferrule 8 is temporarily fixed to a ferrule holder 9 with a screw 11, the part higher than the part of a ferrule chip 7 press-inserted in the ferrule 8 is fused by laser welding from the surface of the ferrule holder 9 to the ferrule 8 at the same time and the ferrule holder 9 is fixed. The screw 11 which is used for the temporary screw 11 is removed after the laser welding.