A control box 10 according to the present invention has at least one electric device 12 and fan unit 17 inside a case 11. In the case 11, a dividing board 15 divides a room into two rooms which include a heated room 30, close to the electric device 12, and a ventilated room 31. First and second openings 24B,24A open the heated and Ventilated rooms 30,31 to the outside of the case 11, respectively. The fan unit 17 is disposed on a window penetrating the dividing board 15 and feeds air from one of two rooms to another.