To provide a polylactic acid resin-based thermoplastic resin composition which is excellent in surface appearance, impact resistance, and thermal stability, and a molding of the composition.

The thermoplastic resin composition contains 0.01-2 pts.wt. of phosphoric acid and/or monosodium phosphate (E) in a resin composition containing 15-60 pts.wt. of a rubber-containing graft copolymer (A), 10-55 pts.wt. of a vinyl-based copolymer (B) containing 50-90 wt.% of a (meth)acrylate-based monomer (a), 0-50 pts.wt. of a (meth)acrylate-based polymer (C), and 5-55 pts.wt. of a polylactic acid resin (D) (the total of the rubber-containing graft copolymer (A), the vinyl-based copolymer (B), the (meth)acrylate-based polymer (C) and the polylactic acid resin (D) is 100 pts.wt.). Relation of melt viscosity (η) between a resin composition (F), comprising the rubber-containing graft copolymer (A), the vinyl-based copolymer (B) and the (meth)acrylate-based polymer (C), and the polylactic acid resin (D) at 220°C and 1,000 s-1 is within the following range: 0.30≤η of the (D) component/η of the (F) component≤0.80.