To visually determine easily and properly that a head has been completed fastened, while preventing the head from being intentionally removed from a fastening device before the head is completely fastened, with a simple structure, when a nut type fastening device is checked, as well as reducing cost.
A checking device includes: a low tubular body 22 having a thick portion 22a formed in a circumferential surface near a seat portion to have a diameter smaller by a required amount than an outer diameter of a case in a fastening device, allowing a lower side of the case to be inserted into an inner periphery at an upper part of the thick portion 22a before fastening operation by the head, and having an easy-to-break shaped portion 23 formed in a part of portions; a ring portion 24 to be externally inserted into the head; and a coupling portion 25 for coupling the ring portion 24 and the low tubular body 22 integrally. The case descends when the head fastening operation is completed in the fastening device, and the lower side of the case moves onto the thick portion 22a to break the easy-to-break shaped portion 23 in the low tubular body 22, thereby determining completion of the head fastening operation.
NISHIDA EIJI
HASHIMOTO FUMIYOSHI
