According to an aspect of the invention, the circumferential position of a protrusion portion of a light guide member is aligned with the position of a second groove portion of a pressing member and a tip portion of the light guide member is inserted into an insertion hole. Next, the light guide member is rotated to align the circumferential position of the protrusion portion of the light guide member with the position of a first groove portion of a mounting hole, and the tip portion of the light guide member is mounted in the mounting hole of a tip portion body. After that, a screw member is inserted into a through hole of the pressing member, is threadedly inserted into a screw hole of the tip portion body, and fixes the pressing member to a base end face of the tip portion body.
