A polypropylene resin composition for molding material, which is excellent in an appearance of weld line and an appearance of tiger stripe and is used for automobile exterior parts and an automobile exterior part comprising the same, are provided. A propylene-based block copolymer composition, comprising 100 parts by weight of a propylene-based block copolymer having an MFR of 50 to 100 g/10 minutes and an Mw/Mn of 7 or less, wherein the propylene-based block copolymer comprises 75 to 95% by weight of a crystalline polypropylene portion and 5 to 25% by weight of an ethylene-propylene copolymer portion, where the ethylene content of the ethylene-propylene copolymer portion is 35 to 45% by weight and the ratio of the weight-average molecular weight of the ethylene-propylene copolymer portion to the weight-average molecular weight of the crystalline polypropylene portion is 3 to 5; 25 to 45 parts by weight of an ethylene-α-olefin copolymer elastomer having an MFR of 1 to 9 g/10 minutes; and 30 to 45 parts by weight of talc having an average particle diameter of 1.5 to 15 μm.