To provide a tank for an aluminum-made heat exchanger and its manufacturing method for facilitating manufacture and reducing manufacturing cost.

This tank 1 for the aluminum-made heat exchanger is provided in an end part of a core composed of a tube and a fin. The tank is composed of a header plate 2 in which an end part of the tube is inserted and a tank body 3 like a thin and long box whose header plate 2 side is opened. The tank body 3 is composed of two members 7, 8 to be joined along the longitudinal direction. At least either of two members 7, 8 is formed by drawing.