To obtain the subject composition suppressed in bleedout of the flame retardant contained and in fuming during its molding, and excellent in impact resistance and flame retaredancy, thus useful in the field of electronic equipment, by incorporating a polyphrnylene ether based resin (composition) with a specific flame retardant and a specific graft copolymer.

This composition is obtained by incorporating (A) 100 pts.wt. of a polyphenylene-based resin (and an aromatic vinyl-based resin) with (B) 1-30 pts.wt. of a condensed phosphoric ester-based flame retardant expressed by formula I or II(Ra-h are each an alkyl, a phenyl or an alkylphenyl; X is a phenylene, a 1-6C alkylene or SO2; (p) and (q) are each an integer of 1-30), and (C) 0.5-30 pts.wt. of a composite rubber-based copolymer obtained by grafting a (epoxy group-containing) vinylic monomer to a composite rubber obtained by incorporating an organosiloxane robber component with a polyalkyl(meth)acrylate rubber component.