A thermoplastic resin composition comprising a graft copolymer (I) which is produced by carrying out the graft polymerization of a monomer mixture (B) comprising an aromatic vinyl monomer and a vinyl cyanide monomer in the presence of an acrylic rubbery polymer (A) and a vinyl copolymer (II) which is produced by carrying out the copolymerization of an aromatic vinyl monomer with a vinyl cyanide monomer, wherein the ratio of the content of the former copolymer to that of the latter copolymer is (30 to 70 parts by weight) : (70 to 30 parts by weight), the graft copolymer (I) has such a property that the ratio (i.e., (±)/(²)) of the gel swelling degree (±) of the acrylic rubbery polymer (A) in toluene to the grafting ratio (²) of the graft copolymer (I) is 0.4 to 2.0, and the thermoplastic resin composition has such a structure that particles of the graft copolymer (I) are aggregated in the thermoplastic resin composition. From the thermoplastic resin composition, a molded article having excellent fluidability, weather resistance and impact resistance can be produced.