It has been reported that the 5182 aluminum sheet shows Lüders band because of dissolved Mg atoms that cause fabrication process problem, especially surface roughness. The examination of serration phenomena has been made after the tensile deformation of the AA/PP/AA sandwich sheets as well as that of the 5182 aluminum. All sandwich sheets and the 5182 aluminum skin showed serration phenomena on their flow curves. However, the magnitude of serration was significantly diminished in the sandwich sheet with high volume fraction of the polypropylene core. According to the results of the analysis of the surface roughness after tensile test, Lüders band depth of the sandwich sheet evidently showed lower than that of the 5182 aluminum skin. The strain rate sensitivity, m-value, of the 5182 aluminum skin was -0.006. By attaching these skins to the polypropylene core, which has relatively large positive value of 0.050, m-value of the sandwich sheets changed to the positive value.