To provide a thermoplastic resin composition for a lamp housing, improving defective phenomena such as powder generated at vibration welding in junction of the lamp housing with another member (a lens and the like), appearance of burr and string-shaped burr, defective phenomena caused by the stringing between a hot mold and a housing material at hot plate welding, and defective phenomena of a bubble generated at welding by irradiation with a laser beam.

The thermoplastic resin composition for the lamp housing comprises (A) a rubber-reinforced resin obtained by polymerizing a vinylic monomer comprising an aromatic vinyl compound and a vinyl cyanide compound in the presence of a gummy polymer having ≥70% content of gel, and (B) at least one polymer selected from a copolymer containing a maleimide-based monomer unit, and a (co)polymer of α-methylstyrene. The content of the gummy polymer derived from the component (A) is 5-30 mass% based on the whole thermoplastic resin composition.