To provide a fastening structure capable of positively detaching a bolt which is hard to detach by taking time, and achieving both theft prevention of a mounting member and maintainability, and to provide a fastening method and a power transmission device.
A fastening tool 91 includes a bottomed cylindrical bolt cover 93 mounted on the bolt 92, and a spherical body 94 stored in the bolt cover 93. The bolt cover 93 includes: an insertion hole 93b into which a screw part 92b of the bolt 92 is inserted; a bottom part 93c abutted on a bottom face 92m of a head part 92a of the bolt 92; a peripheral wall part 93d projecting from an outer peripheral part of the bottom part 93c and surrounding the periphery of the head part 92a of the bolt 92; and a plurality of bent parts 93e provided at projecting ends of the peripheral wall part 93d and bent toward an axis O of the peripheral wall part 93d from the projecting ends of the peripheral wall part 93d. The spherical body 94 is stored in the bolt cover 93 to be positioned between distal ends 93m of the bent parts 93e and the head part 92a of the bolt 92.
OTAKA KENJI
Eigarou Ariga