To provide a fastening structure having a bolt hard to unfasten but capable of being fastened with spending time and simultaneously achieving both theft-prevention and maintenance property of a fastened object, a method for setting up the fastening structure, and a power transmission.

A theft-prevention fastener 91 from installing an SBW motor 21 externally on a transmission case 11 is provided. The fastener 91 includes a bolt 92 having a head 92a and a screw thread portion 92b provided integrally with the head 92a, a bottomed cylindrical bolt-cover 93, and a cap member for closing the opening end 93a of the bolt cover 93. The bolt cover 93 includes a bottom having an insertion hole for the screw thread portion 92b and contacting the bottom of the 92a, and a holding portion projected from the outer periphery of the bottom and surrounding the head 92a of the bolt 92. When the screw thread portion 92b is screwed to a screw groove 11b of the transmission case 11, the bottom of the bolt cover 93 is placed between the bottom surface of the head 92a and fastening portions 41a, 41b, 41c of a bracket 41.