PURPOSE: To make it possible to form a resin composition which is excellent in flame retardancy and does not undergo resin drip or opening at the part in contact with a flame when a molding is burnt, by mixing a polyphenylene ether resin with a styrene copolymer containing silane compound monomer units, a flame retardant and a polytetrafluoroethylene resin.

CONSTITUTION: This resin composition is composed of 10W70wt.% polyphenylene ether resin (A), 10W89wt.% styrene copolymer (B) containing silane compound monomer units or a mixture of this copolymer with a polystyrene resin, 1W20wt.% flame retardant (C), and 0.005W0.1wt.% polytetrafluoroethylene resin (D). The content of said silane compound monomer units is 0.005W0.05wt.% based on the total weight of the composition. Although a flame retardant which is usually used to impart flame retardancy to a thermoplastic resin or a thermosetting resin can be used as said flame retardant, an aromatic phosphate flame retardant is particularly desirable.