comprises a mixture of a resin having an average particle diameter of not more than 1000 u03bcm selected from wholly aromatic polyamide polyimide polyamideimide a copolymer of the wholly aromatic polyamide the polyimide or the polyamideimide or a mixture of the above mentioned polymers and a metal hydrate the flame retardant resin composition contains 50 to 200 parts by mass of the flame retardant composition to 100 parts by mass of a thermoplastic resin or a thermosetting resin application_number US 87370710 A description resin having an average particle diameter of not more than 1000 u03bcm as an a component used in the present invention forms a char layer on the surface of molded products and has the function of restraining spreading fire and fuming during incipient fire the resin is at least one kind selected from wholly aromatic polyamide polyimide polyamideimide a copolymer thereof or a mixture thereof these resins may be used singly or in proper combination of not less than two kinds when the average particle diameter of the above mentioned resin exceeds 1000 u03bcm a resin in a flame retardant composition is not melted at molding temperature of a thermoplastic resin in the case of blending the flame retardant composition with the thermoplastic resin so that resin pellets can not be produced the average particle diameter of the resin in a flame retardant composition is preferably not more than 800 u03bcm more preferably not.