Abstract: A battery module with a cooling system capable of ventilating a uniform amount of air through the respective unit cells. The battery module includes a plurality of unit cells spaced from each other and a housing for accommodating the unit cells therein. The housing has an inflow guide side inclined with respect to the direction perpendicular to the interfacial surfaces of the plurality of unit cells, an air inlet for introducing a temperature controlling air, and an air outlet for discharging the air ventilated through the unit cells.