To provide a nut member in which a female screw of a nut is securely screwed with a screw, and its manufacturing cost is reduced by its simplified structure.

The nut member comprises: a nut 1 in which a rotational shaft 12 is projected from side faces opposed to each other and sandwiching the female screw 11 therebetween; a washer 2 having a pair of leg pieces 23 which are extended from a washer 22 forming an insertion hole 21 of the screw A, and having a guide groove 24 in which the rotational shaft 12 of the nut 1 is rotatably and slidably inserted into the leg pieces 23; and a spring mechanism 3 urging and holding the nut 1 at a rotation angle where the female screw 11 matches with the insertion hole 21 of the screw A formed in the washer 2.