To provide a method for casting an aluminum alloy, which eliminates disadvantage in a conventional technology by combining compositional design and control of solidifying speed so as to facilitate the use of a complicated cast component at a high temperature.

In an embodiment of the invention, the aluminum alloy contains: a rare earth element of approximately 1.0 to 20.0% (by weight%) chosen from ytterbium and gadolinium; at least one of the second rare earth element of approximately 0.1 to 10.0% (by weight%) chosen from gadolinium, ytterbium, yttrium, erbium and cerium; and an alloy element of a trace amount. The combination of compositional design and control of solidifying speed brings about a structural improvement and uniform distribution of an insoluble dispersoid containing eutectic rare earth elements. Further the structural improvement and uniform distribution of eutectic phase exerts better corrosion resistance than the conventional aluminum alloy.