The present invention relates to a reinforced thermoplastic resin composition comprising at least an amorphous thermoplastic resin (A), a flame retardant (B), fibrous calcium silicate (C) and an inorganic material (D) comprising talc and/or mica, the content of flame retardant (B) being 0.01 to 30 parts by weight based on 100 parts by weight of the amorphous thermoplastic resin (A); the content of fibrous calcium silicate (C) in said composition being 3 to 30% by weight, and the content of the inorganic material (D) comprising talc, mica or mixture thereof in said composition being 3 to 30% by weight.