Patent ID: 8353227

Claim:
A fastening device comprising: a supporting member having a hole; a collar member fitted to said hole, said collar member having a predetermined radial width; a bolt member mounted to an end of a supported member and inserted through said collar member; a nut engaged with a threaded portion of said bolt member for releasably fixing said supported member to said supporting member; wherein a washer is interposed between a bolt head of said bolt member and one end of said collar member; said washer being in contact with said bolt head to form a first contact surface and being in contact with said collar member to form a second contact surface; and a relief portion formed in the bolt head and having a predetermined radial width being greater that the predetermined radial width of said collar, said relief portion overlapping said second contact surface and being adjacent to said first contact surface as viewed in the axial direction of said bolt member for allowing deformation of said washer.