To obtain a thermoplastic resin composition capable of preventing the degradation of a thermoplastic resin in a melt kneading process and molding process and fully exhibiting the reinforcing effect of wollastonite by treating the surface of a fibrous β-wollastonite with a specific phosphate ester.

This composition is obtained by mixing (A) one or more kinds of thermoplastic resins selected from the group consisting of a polyalkyleneterephthalate, a polyalkylenenaphthalate, a copolyetherimide-ester, a copolyether-ester, an aromatic polycarbonate, a rubber modified homopolymer or copolymer of a vinyl aromatic monomer, a polyphenylene-ether, a polyamide or blended products of these, and blended products of these with other polymers, and (B) a fibrous β-wollastonite surface-treated with at least one of phosphate esters expressed by formulas I to IV (R, R' or R" are each a ≥6C hydrocarbon).