A thermoplastic resin composition that includes 100 parts by mass of a first vinyl (co)polymer (I) that is produced by (co)polymerization of at least one monomer component selected from the group consisting of aromatic vinyl compounds, vinyl cyanide compounds, and other vinyl monomers copolymerizable with these compounds, and 1 to 100 parts by mass of a vinyl copolymer (II) that is produced by copolymerization of a vinyl cyanide compound and another vinyl monomer copolymerizable with the vinyl cyanide compound and in which the content of the vinyl cyanide compound component in an acetone soluble fraction of the copolymer ranges from 0.1% to 15% by mass.