Patent ID: 8821092

Claim:
A fastening system comprising: a one side member including a non-circular attachment hole having an opening portion formed at a part of a circumference of the non-circular attachment hole; an opposite side member including an insertion hole; and a fastening member for use in coupling between the one side member and the opposite side member wherein the fastening member comprises: a bolt including a shaft portion configured to be inserted in the attachment hole from the opening portion of the attachment hole and having a male screw formed at least a distal end side of the shaft portion, and a head portion formed at a proximal end side of the shaft portion and configured so as to be unable to pass through the attachment hole in an axial direction of the shaft portion when the shaft portion is inserted through the attachment hole, the shaft portion being configured in such a manner that the opposite side member is attached to the shaft portion; a washer including a through-hole, through which the shaft portion of the bolt is inserted, the washer being configured to sandwich the one side member between the washer and the head portion; and a nut configured to be screwed with the male screw of the bolt and configured to couple the one side member and the opposite side member, wherein the shaft portion of the bolt includes a non-circular relative rotation prevention portion at a head portion side of the shaft portion, the relative rotation prevention portion being configured to abut against the non-circular attachment hole in a rotational direction to prevent a relative rotation between the bolt and the one side member.