Provided is a thermoplastic resin composition which includes: a graft copolymer prepared by graft-polymerizing an aromatic vinyl-based monomer and a vinyl cyan-based monomer onto an acrylic rubber polymer; a first matrix copolymer including a C1-C3 alkyl (meth)acrylate-based monomer unit, an aromatic vinyl-based monomer unit and a vinyl cyan-based monomer unit; a second matrix copolymer including a C1-C3 alkyl (meth)acrylate-based monomer unit, an aromatic vinyl-based monomer unit and a vinyl cyan-based monomer unit; and an additive including a polymer including a C1-C3 alkyl (meth)acrylate-based monomer unit, wherein the first matrix copolymer and the second matrix copolymer have different weight-average molecular weights, specifically, a thermoplastic resin composition which allows high gloss, high hardness, high weather resistance and reduced whitening to be realized.