The automobile industry has recently been manufacturing cars using aluminum alloys, either #5000 or 6000. However, the forming of these materials as sheet metal by static methods, such as hydro bulge forming or general punching, is very difficult because these materials allow little elongation compared to conventional steel. In order to examine the application of explosive forming, we tried free forming aluminum alloy as the basis of the study. We compared the elongation of the alloy when explosive forming was used to that produced by punching. It was consequently found that the amount of elongation was larger for deformation produced by explosive forming. Recognizing the importance of investigating the deformation process of aluminum plate by explosive forming, we pursued a theoretical framework for elucidating this, completing a numerical simulation by the FDM method. This simulation permits an evaluation of the detonation process of the explosive, the propagation process, and the deformation process of the aluminum alloy.