The thermoplastic resin composition of the present invention is made of:(a) 5-95 weight % of polypropylene;(b) 95-5 weight % of a polyester; and(c) 2-70 parts by weight, per 100 parts by weight of the total of (a) + (b), of a polyolefin-polyester graft copolymer.The polyolefin-polyester graft copolymer is constituted by 10-90 parts by weight of a polyester having an intrinsic viscosity [n] of 0.30-1.20 and an end carboxyl group content of 15-200 milliequivalent/kg; and (B) 90-10 parts by weight of a modified polyolefin having an epoxy group or carboxyl group content of 0.2-5 mol % and a weight-average molecular weight of 8,000-140,000. This thermoplastic resin composition may further contain (d) a modified polypropylene grafted with an unsaturated carboxylic acid or its anhydride.