To provide a locking member which prevents the separation of a bolt member and a retaining object member and may not disturb relative rotation of the bolt member and the retaining object member in an assembly in which the bolt member is passed through the retaining object member equipped with a passing hole for passing through the bolt member.

This locking member comprises a bolt member 2 having a screw at least on its one end side, a locking member 1 which has length that approximately goes around the bolt member 2 and fitted along the inside of the thread groove of the bolt member 2 and whose entire shape has a spiral shape, and a retaining object member having a passing hole through which the bolt member 2 is passed. This locking member is so formed that the locking member 1 is fitted and attached to a desired position in the thread groove of the bolt member 2 after the bolt member 2 is passed through the passing hole of the retaining object member, thereby the separation of the bolt member 2 and the retaining object member can be prevented, and the relative rotation of the bolt member 2 and the retaining object member may not be disturbed.