The present invention provides a thermoplastic resin composition which includes: A-1) a first copolymer including a first conjugated diene-based polymer, an alkyl (meth)acrylate-based monomer unit, and an aromatic vinyl-based monomer unit, wherein the first conjugated diene-based polymer has an average particle diameter of 0.05 to 0.2 µm; A-2) a second copolymer including a second conjugated diene-based polymer, an alkyl (meth)acrylate-based monomer unit, and an aromatic vinyl-based monomer unit, wherein the second conjugated diene-based polymer has an average particle diameter of 0.23 to 0.5 µm; B) a third copolymer including an alkyl (meth)acrylate-based monomer unit and an aromatic vinyl-based monomer unit; and C) a plasticizer having a viscosity of 700 to 10,000 cP, wherein the plasticizer is included at 0.3 to 5 wt%. The thermoplastic resin composition is excellent in all of transparency, impact resistance, and flowability.