PURPOSE: To obtain a resin composition excellent in heat resistance, strength, stiffness, etc., useful for an automotive exterior trim part such as a door handle or a bumper by compounding two resin components having poor compatibility with each other, an inorganic filler and two specific silane-based coupling agents.

CONSTITUTION: This composition is composed of (A) the first resin component 5 of preferably a PP resin, (B) the second resin component 6 of preferably a polyamide resin having higher heat resistance than the component A, (C) an inorganic filler 3 of diatomaceous earth preferably having fine holes of >0.1μm in hole diameter, (D) the first silane coupling agent having a functional group R1 compatible with the component A and a functional, group X1 compatible with the component C and (E) the second silane coupling agent having a functional group R2 compatible with the component B and a functional group X2 compatible with the component C. Further, the composition is obtained by treating the component C with the components D and E, melting and kneading the treated component C with the component A and melting and kneading the obtained composite material with the component B.