A nut member 10 facilitates an adjustment of the optical axis of a light, has excellent handleability, and includes a flange portion 11 to be supported by an attachment portion 6 disposed on the back side of a vehicle lamp member 1, and a leg portion 15 protruding to the front from the flange portion 11 and to be elastically deformed and fastened to the attachment portion 6, the lamp member 1 having an optical axis 100 to be adjusted by handling a screw 8 inserted into an insertion hole 22 formed over from an inside of the flange portion 11 to the leg portion 15. Before an insertion of the screw 8, a screw thread 14 of a female screw portion 13 has been formed on an inner surface of a flange insertion pass (insertion hole 22) to extend one round in a circumferential direction.