A graft copolymer resin obtainable by graft-polymerizing a vinyl monomer comprising a vinyl cyanide monomer and an aromatic vinyl monomer to a rubbery polymer, in which a free resin contained in the graft copolymer resin comprises 10 to 35% by mass of a constituent unit derived from a (meth)acrylic acid alkyl ester having an alkyl group containing 4 or more carbon atoms, based on the total amount of the free resins, and the graft copolymer resin satisfies at least one of the following requirements (1) and (2): (1) the rubbery polymer comprises a constituent unit derived from a (meth)acrylic acid alkyl ester having an alkyl group containing 4 or more carbon atoms; and (2) the vinyl monomer further comprises a (meth)acrylic acid alkyl ester having an alkyl group containing 4 or more carbon atoms.