To provide a locking construction requiring unfastening torque larger than fastening torque concerning the screw locking construction in screw parts such as bolts and nuts or washer parts.

In the bolt or male screw part, the nut or female screw part, or the washer part, a guide hole is formed in a bearing surface facing a movement direction of the screw part with respect to turning of the screw in a fastening direction, in an outer peripheral surface of the screw part, or in a bearing surface of the washer part. A thrust member longer than a depth of the guide hole is put in the guide hole. An end of the thrust member projects from the bearing surface or the outer peripheral surface of the screw part before the screw is fastened and the thrust member is inclined or bent by fastening of the screw.