In a casing, a printed circuit board is arranged such that a first side of the printed circuit board has a first angle of α° with respect to a first side surface plate. A cooling device is arranged to have a second angle of β with respect to the first side surface plate. Accordingly, an amount of cooling air flowing in and out via an air intake port and an air discharge port may be increased. Furthermore, by reducing the angle of the change in the flow direction of the cooling air flowing over the printed circuit board, the cooling air flowing over the printed circuit board may be made to efficiently flow through an air discharge port 119a. Furthermore, the efficiency with which a heat-generating component on the printed circuit board is cooled may be improved.