A thermoplastic resin composition comprising a blend obtainable by blending 0.1 to 99% by weight of (a) a fluorine-containing polymer having a number-average molecular weight of 2000 to 1000000 and having hydroxy group or epoxy group at least at one of end portions of a main chain and side chain of the polymer, and 1 to 99.9% by weight of (b) a heat resisting thermoplastic resin having a crystalline melting point or glass transition temperature of not less than 150.degree. C. The present invention can provide a composition comprising various heat resisting thermoplastic resins and a fluorine-containing polymer having a functional group which is capable of developing an affinity with said resins and forming a uniform dispersion.