To provide a method for generating a larger friction resistance force in a friction resistance type self-locking nut.

A bulking agent is inserted into a space of a groove which is formed toward a screw surface of a bolt when a nut having a V shape groove crossing a screw turn direction at right angles and opened toward a screw turning center engraved on a screw surface of the forming nut is screwed and fastened to a bolt to cover and fill a screw. The bolt and the nut are stuck through the bulking agent, a degree of integration is increased, and wedge action resulting from the action of the bulking agent filling the groove on the screw surface of the bolt is added. Consequently, the large friction resistance force is obtained and the problem is solved.