To constitute a structure that is miniaturized with light weight, regulates a fastening force, holds a proper fastening force even if a drape (collapse) of a material to be fastened is generated, and can simply and easily inspect a fastening state, and to prevent the loosening of bolt fastening.

The structure is constituted of an elastic body 1, a ring 2 and a collar 3, and the height of the ring 2 is made to be a height at which a preset gap (G) is formed between the collar 3 and the structure while the ring contacts with the elastic body at a free height of the elastic body 1, and the fastening force is detected by the abutment of the ring 2 on the collar 3 resulting from the deformation of the elastic body by the fastening force of a blot at the bolt fastening. Furthermore, when a nut (bolt) is turned in a direction in which the nut is loosened, the elastic body is pressurized by a cam, an axial force is increased, and a lock effect of the bolt fastening is improved.