A fastener having a small overall structure and exhibiting a strong fastening torque. The fastener being fixed to a member (B) to be fastened through rotational operation and continuously applying a fastening torque to the member (B) to be fastened, characterized by comprising a removable stopper (2) for restraining a torsion coil spring (1) provided with an end part (13) being secured to an object (A) having one end part fixed with the member (B) to be fastened and formed into a winding shape so that the object (A) can be fitted over the member (B) to be fastened from the axial direction.