Disclosed is an electric Al—Zr alloy plating bath containing an aluminum halide (A), one or more compounds (B) selected from the group consisting of N-alkylpyridinium halides, N-alkylimidazolium halides, N,N′-alkylimidazolium halides, N-alkylpyrazolium halides and N,N′-alkylpyrazolium halides, and a zirconium halide (C). The molar ratio between the aluminum halide (A) and the compounds (B) is from 1:1 to 3:1. The electric Al—Zr alloy plating bath further contains an aromatic organic solvent (D), an organic polymer (E) and one or more additives (F) selected from brightening agents.