The present invention provides a flame-retardant resin composition including a matrix resin and at least granular flame-retardant fine particles having a volume average particle diameter in said range of about 1 to about 500 nm. The invention also provides a flame-retardant resin composition including a matrix resin; at least flame-retardant fine particles having a volume average particle diameter in said range of about 1 to about 500 nm and comprising inorganic fine particles of a hydrated metal compound or an inorganic hydrate. The invention provides a flame-retardant-resin formed article, formed form said flame-retardant resin composition by one or more forming machines selected from a press molding machine, an injection molding machine, a molding machine, a blow molding machine, an extrusion molding machine, and a fiber forming machine; and a process for producing flame-retardant resin compositions, including blending at least a matrix resin and flame-retardant fine particles by one or more kneading machines selected from a roll mill, a kneader, a Banbury mixer, an intermixer, a uniaxial extruder, and a biaxial extruder.