The present invention relates to a reinforced thermoplastic resin composition having excellent moldability, processability, and mechanical strengths, as well as being capable of improving the drop impact resistance (surface impact strength determined by a falling ball test). The reinforced thermoplastic resin composition of the present invention includes 10 to 60% by mass of a graft copolymer (A) having a graft chain (A2) grafted to a rubber polymer (A1); 40 to 90% by mass of a matrix polymer (B) which includes one or more types of polymers selected from the group consisting of a vinyl-based copolymer (B-1), a polycarbonate resin (B-2), and a polyester resin (B-3); 0.1 to 50 parts by mass of an inorganic filler (D); and 0.5 to 20 parts by mass of a glycidyl ether unit-containing polymer (E) having a mass average molecular weight of 3,000 to 200,000.