The present invention provides a thermoplastic resin composition comprising 100 mass parts of a polycarbonate resin composition comprising 50 to 95 mass % of (A) a polycarbonate resin and 50 to 5 mass % of (B) a polylactic acid based resin and 5 to 65 mass parts of (C) a vinyl based graft copolymer. The above thermoplastic resin composition comprising the polycarbonate resin and the lactic acid based resin and endowed with a mechanical characteristic of polycarbonate and an excellent fluidity of polylactic acid in combination is improved in a hydrolysis resistance and provides a molded article further improved in an impact resistance and a thin-walled falling weight impact strength. A rise in the above characteristics makes it possible to use the plastic molded articles over a long period of time, and not only the thin-walled molding property and the portability are improved, but also the thermoplastic resin composition of the present invention can industrially advantageously be used as well for large-sized molded articles. In the thermoplastic resin composition of the present invention, use of the polycarbonate-polyorganosiloxane copolymer as the polycarbonate resin component makes it possible to improve as well the flame retardancy and advantageously use the thermoplastic resin composition of the present invention for office automation equipments, information and communication equipments, car parts, building components, home electric appliances and the like.