PURPOSE: To provide excellent workability for optical axis adjustment.

CONSTITUTION: Engagement teeth 63 engaged with a tool which rotates a rotating member 6 from the direction of crossing the rotational axis 0-0 of the rotating member 6 and a hexagon head 64 to rotate the rotating member 6 from the direction of the rotational axis 0-0 of the rotating member 6 are provided at the other end of a rotating member 8. As a result, optical axis adjustment work can be done from the direction of the rotational axis 0-0 of the rotating member 6 and from the direction perpendicular thereto as well. A holder 7 is provided with a guide 70 to guide the tool from the direction perpendicular to the rotational axis 0-0 of the rotating member 6. The tool can thus be guided by the guide 70 of the holder 7 to ensure optical axis adjusting work. This improves workability for optical axis adjustment.