A disclosed unit device: two first circuit boards provided apart from each other in a horizontal direction; heat generating components respectively provided on the two first circuit boards; two second circuit boards provided between the two first circuit boards, arranged to stand at a distance from each other, and each having an opening; and a fan provided between the two second circuit boards and configured to cool the heat generating components on the two first circuit boards by drawing air through the opening of one of the second circuit boards and by expelling the air through the opening of the other second circuit board.
