To obtain a thermoplastic resin composition excellent in molding flowability and capable of imparting molded articles excellent in impact resistance, heat deformation resistance, molding flowability and surface appearance by containing a rubber component treated to enlarge particle size.

This thermoplastic resin composition comprises (A) 5-95 pts.wt. of a polyamide resin, (B) 5-95 pts.wt. of an unsaturated carboxylic acid- containing copolymer which comprises 40-80wt.% aromatic vinyl compound, 15-50wt.% vinyl cyanide compound, 0.1-20wt.% unsaturated carboxylic acid compound and 0-30wt.% other copolymerizable vinyl-based compound and (C) 5-50 pts.wt. graft copolymer obtained by graft polymerizing 60-5wt.% vinyl-based compound in the presence of 40-90wt.% particle enlarged rubber having 0.1-2.0μm average particle size and obtained by adding (D) 0.1-15wt.% acid group- containing copolymer latex having 0.05-0.5μm average particle size and treating to enlarge the particle size. The component D comprises 5-20wt.% unsaturated acid monomer such as acrylic acid, 5-30wt.% alkyl acrylate monomer and 20-80wt.% alkyl methacrylate monomer, etc.