A polypropylene-based resin composition containing 0.001 to 10.0 parts by weight of benzoic acid with or without substituent(s) on its benzene ring and/or an acid anhydride of benzoic acid, with or without substituents on its benzene rings, to 100 parts by weight of a polypropylene-based resin is disclosed. The resin can generate mouldings with improved rigidity or transparency.