To obtain an excellent thermoplastic resin composition having a number of properties of weather resistance, shock resistance, pigment coloring property, chemical resistance and transparency.

This composition is a thermoplastic resin composition comprising 15 pts.wt. or more and less than 50 pts.wt. of a graft copolymer (I) obtained by graft-polymerizing a monomer mixture (B) consisting of an aromatic alkenyl compound and a vinyl cyanide compound in the presence of a composite rubber (A) having a weight average particle size of 0.08-0.16 μm consisting of a polyorganosiloxane (a-1) and a polyalkyl acrylate (a-2) and exceeding 50 pts.wt. and 85 pts.wt. or less of a polymethyl methacrylate resin (II) [(I)+(II)=100]. The content of the composite rubber (A) in the thermoplastic resin composition is 10-25 pts.wt.