The present invention provides a resin composition which is excellent in balance of mechanical properties and processability, solvent resistance and chemical resistance. This composition comprises:(a) a polyphenylene ether resin,(b) a thermoplastic polyester resin, and(c) a compound represented by the formula:(HO)mR.sup.1 (COOR.sup.2)n wherein R.sup.1 represents a straight or branched chain saturated aliphatic hydrocarbon group of 2-20 carbon atoms, R.sup.2 represents a hydrogen atom or an alkyl or aryl group of 1-20 carbon atoms and R.sup.1 and R.sup.2 may be identical or different and m and n each represents an integer of 1 or more or a derivative thereof.This composition may further contain a rubber-like polymer.