A device for attaching busbars of square or rectangular cross section on a support rail using electrically non-conducting support elements, which can be connected with the support rail and form a busbar receptacle adapted to the cross section of the busbar. With a simple fastener, assembly is considerably simplified because two post-shaped supports per busbar can be attached as support elements on the support rail, wherein spacing between the supports is matched to the width of the busbar and a height is matched to the thickness of the busbar. A base plate is arranged between the two supports, which insulates the busbar receptacle against the support rail and which is captively held between the holders. The ends of the supports facing away from the support rail can be closed by a strip.