Abstract: The polypropylene-based resin composition of the invention consists basically of (a) a polypropylene resin or a block copolymer of propylene and ethylene of specified ethylene content specified in terms of the melt index and the isotacticity relative to the isotactic pentad of the propylene moiety and (b) a talc powder specified in terms of the average particle diameter and the average aspect ratio of particles. The resin composition has good blow-moldability and is capable of giving molded articles having excellent mechanical strengths and dimensional accuracy to be useful, for example, as a material of automobile bumper beams.