It is a purpose of the present invention to provide a flame retardant resin composition having a high level of flame retardancy and excellent physical properties and a molded article thereof.The flame retardant resin composition comprises: (A) 100 parts by weight of a resin component (component A) containing polylactic acid (component A-1); (B) 10 to 50 parts by weight of an organic phosphorus compound represented by the following formula (1) (component B): (in the above formula, the phenyl group may have a substituent); (C) 5 to 30 parts by weight of a hydrogenated styrene-based thermoplastic elastomer (component C); and (D) 1 to 10 parts by weight of talc (component D).