An aluminum alloy contains at least 0.0001 mass % and not more than 0.03 mass % of copper, at least 0.0005 mass % and not more than 0.2 mass % of silicon, at least 0.5 mass % and not more than 4 mass % of manganese and at least 0.5 mass % and not more than 3 mass % of iron, and the rest contains aluminum and unavoidable impurities. The aluminum alloy further contains at least one of at least 0.01 mass % and not more than 0.5 mass % of chromium, at least 0.01 mass % and not more than 0.5 mass % of titanium and at least 0.01 mass % and not more than 0.5 mass % of zirconium. An aluminum alloy foil is prepared by heating up the aluminum alloy to a temperature of at leas 350° C. and not more than 580° C., holding the same immediately after the heating up or retaining an ingot of the aluminum alloy at a temperature of at least 350° C. and not more than 530° C. for not more than 15 hours, thereafter performing hot rolling at a starting temperature of at least 350° C. and not more than 530° C., thereafter performing cold rolling and thereafter performing softening.