A moldability modifier capable of improving molding processability, and a polypropylene resin composition using the same suitable for automobile exterior parts are provided. The invention relates to a moldability modifier comprising propylene block copolymer (A) containing from 80 to 98 wt % of a propylene homopolymer portion (A1) and from 2 to 20 wt % of a propylene/ethylene random copolymer portion (A2), wherein the MFR of (A1) is 300 g/10 min or more, the ethylene content of (A2) is from 10 to 70 wt %, the [η] of (A2) is 6.5 dl/g or more, and the MFR as a whole is 40 g/10 min or more; and propylene block copolymer (B) containing from 20 to 79 wt % of a propylene polymer portion (B1) and from 21 to 80 wt % of a propylene/ethylene random copolymer portion (B2), wherein the MFR of (B1) is 20 g/10 min or more, the ethylene content of (B2) is from 20 to 70 wt %, the [η] of (B2) is from 2.5 to 9.0 dl/g, and the MFR as a whole is from 0.1 to 50 g/10 min; and a polypropylene resin composition using the same.