A method of separating a vulcanized or unvulcanized rubber into a rubber ingredient and a filler ingredient such as carbon black which comprises liquefying the vulcanized or unvulcanized rubber at ordinary temperature and ordinary pressure; and a method of separating from a rubber composite a component other than those. The methods comprise immersing, optionally with stirring, a rubber composite or a vulcanized rubber composition each in the form of a block in an organic solvent containing 0.01 to 50% peroxide such as benzoyl peroxide to liquefy the vulcanized rubber composition in the solvent and separating the filler ingredient and other components by centrifugal separation, membrane separation, or decantation.