Disclosed is battery module, which includes a cell assembly having battery cells arranged side by side in one direction and air channels formed at the intervals of the battery cells, and an inlet duct mounted to a front surface of the cell assembly at which the air channels are located to distribute a cooling air to the air channels. The inlet duct includes an air inlet disposed to face air channels, which are located in a central region in the arrangement of the air channels, at a location spaced apart therefrom, a cooling fan being installed at the air inlet to introduce the cooling air; and a guide vane composed of a plurality of plate barriers respectively extending obliquely toward the air channels based on the air inlet at a predetermined acute angle to distribute the flow of air.