To provide a composite resin composition excellent in the balance among impact resistance, flowability and rigidity, having a low coefficient of linear expansion, and excellent in chemical resistance and weatherability.

A resin composition is obtained by blending 20-70 pts. of a graft polymer prepared by polymerizing an aromatic vinyl monomer, a vinyl cyanide monomer and copolymerizable other monomer in the presence of a rubbery acrylic ester polymer and having a particle diameter of 100-300 nm and a crosslinkage with a gel content of 50-95%, with 80-30 pts. of a rigid polymer prepared by copolymerizing an aromatic vinyl monomer, a vinyl cyanide monomer and copolymerizable other monomer, wherein the content of the vinyl cyanide monomer in the rigid polymer is 30-50% and wherein the difference between the content of the vinyl cyanide monomer units in the acetone solubles of the resin composition and the content of the vinyl cyanide monomer units in the total monomer units in the acetone insolubles except for the rubbery polymer is 5% or greater. The composite resin composition is obtained by blending 100 pts. of the resin composition with 1-50 pts. of an inorganic or organic filler.