Thermoplastic resin composition

A thermoplastic resin composition comprising:

• a graft copolymer (A) obtained by graft polymerization of aromatic vinyl monomers and monomers other than maleimide monomers that can be copolymerized with the aromatic vinyl monomers under the presence of a rubbery polymer;
• a copolymer (B) obtained by polymerization of only maleimide monomers and at least one type of other monomers selected from the group consisting of aromatic vinyl monomers, vinyl cyanide monomers, amide monomers, unsaturated carboxylic acid monomers, and combinations thereof;
• a copolymer (C) having a reduced viscosity of less than 1.0 dl/g obtained by polymerization of aromatic vinyl monomers and monomers other than maleimide monomers that can be copolymerized with the aromatic vinyl monomers;
• and
• a copolymer (D) having a reduced viscosity of 1.0 to 3.0 dl/g obtained by polymerization of aromatic vinyl monomers and monomers other than maleimide monomers that can be copolymerized with the aromatic vinyl monomers, wherein
• the content of the graft copolymer (A) is 10 to 60 mass %, the content of the copolymer (B) is 1 to 20 mass %, the content of the copolymer (C) is 10 to 88 mass %, and the content of the copolymer (D) is 1 to 10 mass %, based on the total amount of the graft copolymer (A), the copolymer (B), the copolymer (C), and the copolymer (D);
• the reduced viscosity is measured after dissolving the copolymer (C) or (D) in N,N-dimethylformamide to make a solution at a concentration of 0.4 g/100 ml then measuring at a temperature of 30° C.