The present invention provides a flame retardant resin composition comprising (A) 100 weight part of a basic resin comprising acrylonitrile-butadiene-styrene copolymer resin and styrene-acrylonitrile copolymer resin; and (B) 10-30 weight part of a bromine-based organic compound flame retardant, and selectively comprising (C) 1-20 weight part of an antimony-based auxiliary flame retardant and (D) 1-10 weight part of one or more compounds selected from the group consisting of metalstearate and stearamide compounds, wherein the bromine-based organic compound flame retardant (B) is octabromodiphenyl ethane. The flame retardant resin composition of the present invention has excellent flame retardancy, impact strength and melt flow index.