To obtain a thermoplastic resin composition having a low flexural modulus, excellent impact resistance, fluidity and a low coefficient of linear expansion of molding.

This resin composition having a low linear expansion and a low rigidity comprises 5-60 pts.wt. of an acrylic acid ester-based copolymer (A), 5-60 pts.wt. of a styrene-based copolymer (B) and a rubber-containing graft copolymer (C) and has 10-25 wt.% rubber content in the resin composition, ≤1,800 MPa flexural modulus of the resin composition and 10.5×10-5 coefficient of linear expansion of molding.