A thermoplastic resin composition and a molded article thereof, respectively excellent in flowability and mechanical properties, and, in a preferred mode, also excellent in low warping property, laser transmittance and laser weldability, is obtained by mixing (B) 0.1 to 4 parts by weight of a polyfunctional compound having three or more functional groups, in which at least one of the terminal structures having the functional groups is a structure containing alkylene oxide units, with (A) 100 parts by weight of a thermoplastic resin, and further provides a molded particle thereof. It is preferred that the (A) thermoplastic resin is one or more selected from a polyester resin and polycarbonate resin.