A thermoplastic resin composition having a high flame retardancy in a thin-wall molded product and a molded article thereof are provided. The thermoplastic resin composition comprises (A) a thermoplastic resin containing a repeating unit having an arylene group, an ether group, and a carbonyl group and (B) a thermoplastic fluorine-containing resin. The weight ratio of the thermoplastic resin (A) and the thermoplastic fluorine-containing resin (B) in the former/the latter is 80/20 to 99/1. The thermoplastic fluorine-containing resin (B) is dispersed in the form of a particle in the thermoplastic resin (A) to form a dispersed phase, and the dispersed phase has an average particle diameter of not more than 3 μm. The thermoplastic resin composition is suitable for forming a molded article having a thin-wall portion with a thickness of not more than 1.5 mm.