PURPOSE: To provide the titled compsn. having excellent mechanical characteristics and moldability, by blending two thermoplastic resins, an epoxy group-contg. (-free) styrene resin and a low-molecular hydrocarbon resin.

CONSTITUTION: 100% (by weight; the same applies hereinbelow) mixture of 5W95% thermoplastic resin (A) (e.g. polyester) having a m.p. of 150W300°C and contg. at least one polar group selected from among COOH, OH and NH2 groups, 0.01W50% epoxy group-contg. styrene resin (B) contg. 0.5W30% copolymerizable unsaturated monomer contg. an epoxy group, 0W90% epoxy group-contg. (-free) styrene resin (C) and 0W90% thermoplastic resin (D) (e.g. polyphenylene ether resin) compatible with component C in an amount of at least 5% of the combined amount of components C and D, 0.01W50% low- molecular hydrocarbon resin (E) (e.g. cumarone/indene resin) and optionally, not more than 3pts.wt. (per 100pts.wt. component A) additives such as nucleating agent, antioxidant, stabilizer, etc., are blended together.