PURPOSE: To shorten the term of works as well as reduce building costs by providing grooves and projecting stripes to both of the mating face of a fastener body and reverse side of washers and by making them engage with each other.

CONSTITUTION: To tapped holes 2 provided to a base body A, bolt-inserting holes 3 of a fastener body 1 are laid over. Projecting stripes and grooves 9 provided over the mating face 4 of the fastening body 1 and projecting stripes and grooves 10 provided over the reverse side of washers 5 are engaged with each other. The fastener body 1 is then fixed to the base body A by screwing bolts 6 down to the tapped holes 2 and by fastening the bolts with nuts 7. Then a panel B is connected to the base body A by inserting the bolts 6, planted to the panel B, into holes 3 from the external side of the fastening body 1, and by fastening the bolts 6 with nuts 7 through washers 5.