An object of the present invention is to prevent an occurrence of flow-mark molding defects to improve an appearance of molded articles, and as a means for achieving the object, a propylene-based block copolymer is used as an appearance improver, the copolymer comprising 80 to 60% by weight of crystalline propylene polymer portion which has an intrinsic viscosity [η]p of 0.90 dL/g or less and 20 to 40% by weight of propylene/ethylene random copolymer portion which has an ethylene content of 35 to 50% by weight and an intrinsic viscosity [η]c of 7.0 dL/g or higher ([η]c/[η]p being 7.5 to 30), in which the propylene-based block copolymer has a MFR of 10 to 50 g/10 min.