PURPOSE: To decrease the Sn, In, Pb and Ga contained as corrosion resistance inhibiting components into Al alloy scrap materials.

CONSTITUTION: The Al alloy scrap materials contg. ≥1 kinds among Mn, Fe, Si, Mg, Cu, Zn, Zr, Cr and Ti as alloy components and further contg. ≥1 kind s among Sn, In, P an Ga are subjected to a heating treatment, in the state of sheet materials, under the conditions of holding for a prescribed period of time at the prescribed temp. within a range from 200 to 450°C in a nonoxidative atmosphere, by which the above-mentioned Sn, In, Pb and Ga are diffused and migrated to the surface parts. The diffused and flocculated surface parts of the above-mentioned components in the Al alloy scrap materials after the above- mentioned heating treatment are then removed, by which the total content of these diffused and flocculated surface parts is decreased to ≤0.005%.