Disclosed is a flame-retardant styrene resin composition wherein there is blended an additive which enhances the flame retardance of a styrene resin when added in a small amount which styrene resin has been imparted with flame retardant properties by a bromine-based flame retardant. The composition is obtained by blending (B) 0.1-30 parts by weight of a bromine-based flame retardant having a bromine content of not less than 50 wt% and (C) 0.01-0.2 parts by weight of a metal phthalocyanine containing one selected from iron, manganese, cobalt, nickel, platinum and palladium, per (A) 100 parts by weight of a styrene resin. |