PROBLEM TO BE SOLVED: To provide a molten Al-Zn-based plated sheet steel not lowering continuous operability, and having excellent corrosion resistance after paint application.SOLUTION: A molten Al-Zn-based plated sheet steel has a plating layer containing, in terms of mass%, Al:25-90% and Bi:0.01-0.1%, and further containing 0.01-10% the total of one or more kinds selected from a group comprising Mg, Ca and Sr.