An aluminum radiator includes a core including a plurality of tubes through which a heat exchange medium flows and fins arranged between the tubes; and a header tank including a pair of header spaced apart from each other and having both ends coupled to the tube, a tank coupled to the header by a brazing and having a heat exchange medium passage formed therein, and end caps coupled to both opening portions of the tank, wherein the tube satisfies an inequality 10 mm≦T≦20 mm, where T denotes an outside width of the tube, and the tank has an inside height (H) of 41 mm or less and satisfies an inequality 1.5≦H/T≦2.5.