PURPOSE: To obtain a resin composition having excellent heat resistance, stability of dimensions in water-absorbed state/mechanical properties and impact resistance, etc., comprising a polyphenylene ether-based resin, a polyamide and a specific resin.

CONSTITUTION: (A) A polyphenylene ether-based resin or a mixture of the resin and a polystyrene-based resin is mixed with (B) a polyamide and (C) a graft- modified polyolefin resin obtained by preparing an aqueous suspension comprising (i) 100 pts.wt. of a polyolefin-based resin, (ii) 0.1-30 pts.wt. of a modifier composed of a glycidyl-containing compound of the formula (Ar is a glycidyloxy- containing 6-23C aromatic hydrocarbon; R is H or methyl), (iii) 0.1-500 pts.wt. of a vinyl-based monomer and (iv) a radical initiator in an amount of 0.001-10 pts.wt. based on total 100 pts.wt. of the components (ii) and (iii), impregnating the component (i) with the components (ii) and (iii) and polymerizing the components (ii) and (iii) to the component (i) to obtain a graft-modified polyolefin-based resin composition. This resin is blended with the components A to C so that the component A is 5-95wt.%, the component B is 95-5wt.% and the component C is 1-100 pts.wt. based on the total of 100 pts.wt. of the components A and B.