In an electronic device, when a 48 V feed system is shifted to a 12 V feed system, in order to supply the same electric power, a current of fourth times needs to flow into a backplane. Also, in an anteroposterior intake and exhaust system, there is a need to form a ventilator through which a cooling air passes in the backplane. Further, there arises a problem that a mechanical strength is deteriorated by provision of the ventilator in the backplane. There is provided a structure in which a pinnate projection is provided on a feed bus bar, and a cooling air is applied to the feed bus bar. Also, the feed bus bar is brought into close contact with an overall surface of the backplane, and electrically and mechanically connected thereto at multiple points, to thereby perform both of cooling and the suppression of stiffness deterioration.