To provide a molding method where superplastic molding for a 6,000 series aluminum alloy sheet can be performed, and also, the generation of cavities upon the superplastic molding can be reduced.

In the superplastic molding method for an Al-Mg-Si based aluminum alloy sheet having a specified composition, the superplastic molding is performed by multi-spindle molding such as blow molding under the conditions satisfying a molding temperature of 520 to 540C and a strain rate of 10-2/s to 1/s, preferably using a pressure medium; thus the maximum equivalent strain amount of 1.0 is obtained, and further, cavities in the molded sheet structure are reduced.