To equally guide in the satisfactory profile, the heat generated from all hierarchical layers allocated in the vertical direction of an air circulation circuit by improving the cabinet of well-known power distribution panel including the air circulation circuit.

An air supplying aperture 15 provided to a base portion 12 is opened toward an air guiding chamber 13. The air guiding chamber 13 is communicated with an air inflow aperture 30 provided to the double-wall type cabinet doors 25, 27 formed as the air distribution device. An air outflow aperture 28 is provided to the internal wall 27 of the cabinet door 25. At the front surface of a device 20 provided opposing to the aperture 28, an intake aperture 21 is provided. The device 20 itself is provided with an intake fan for taking the cooling air from the air distribution device of the cabinet door 25. The warm air flowing from the rear surface of the device 20 is exhausted from the internal chamber via a ventilation hole 24 of the rear surface 23.