The objective of the present invention is to provide a thermoplastic resin composition excelling in translucency, impact resistance, heat resistance and fluidity, particularly a thermoplastic resin composition that in the production of thermoplastic resin molded items through extrusion processing, molding processing, etc., permits a wide tolerance range of processing conditions, such as low susceptibility to quality deterioration by thermal history, excelling in translucency, impact resistance, heat resistance and fluidity; and a molding thereof. The present composition comprises a rubber-reinforced resin consisting of a rubber-reinforced copolymeric resin obtained by polymerization of a vinyl-based monomer including an aromatic vinyl compound in the presence of a rubbery polymer having refractive index in the range from 1.520-1.580, or a mixture of this rubber-reinforced copolymeric resin and a (co)polymer of the above vinyl-based monomer, and a polycarbonate resin in specified ratio, and further comprises a phosphoric compound.