PURPOSE: Resin compositions with high flame tetardancy and mechanical properties which are composed of an aromatic polycarbonate, a specific graft copolymer, a flammable thermoplastic resin, a flame retarder, an auxiliary flame retarder and a specific inorganic compound.

CONSTITUTION: Said composition comprises (a) 5W90wt% of an aromatic polycarbonate, (b) 5W20wt% of a graft copolymer that is prepared by grafting at least one of vinyl monomers selected from the group consisting of methacrylate ester monomers, aromatic vinyl monomers, vinyl cyanide monomers onto a butadiene polymer or a copolymer containing 50% or more butadiene, (c) 0W80% of a combustible thermoplastic resin other than (a) and (b), (d) a flame retarder (d) an auxiliary flame retarder and (e) 5W20% of an inorganic substance selected from caoling clay minerals (SiO2/Al2O3 weight ratio is 95W30/5W70), montmorillonite clay minerals and talc clays