PURPOSE: To decrease the number of parts, to reduce the size and to simplify the structure by providing the receptacle of optical parts connectable with an optical fiber cable and a male or female screw structure to a holder for fixing a light emitting or a photodetecting element, and using a stopper in common use as an attachment base.

CONSTITUTION: This structure consists of the receptacle 1 which has a screw part 2 on the outer circumferential surface and is connectable with an optical fiber, the holder 8 which contains an optical element 6 and is connected to the receptacle 1 through the 2nd screw part 9 formed on the inner circumferential surface for engagement with the 1st screw part 2, and an attachment base 3 sandwiched between the receptacle 1 and optical element 6. The optical element 6 is inserted into the holder 8 from the side of an electrode 7. At this time, the electrode 7 is drawn out of the electrode through hole 10 of the holder 8. In this state, one end of the holder 8 is inserted into the holder fixation hole 4 of the attachment base 3 and when the receptacle 1 is rotated so that the screw part of the receptacle 1 is fitted to the screw part 9 of the holder 8, the receptacle 1 abuts to the attachment base 3 eventually to complete the fixation of four optical parts.