To provide a method for improving the fractionating and dispersing efficiency on the upstream of a fractionating device and also improving easily the recovering efficiency of the air fractionating efficiency and also providing a fractionating device thereof.

An air fractionating device 6 is provided with a crusher 1 for crushing a material to be crushed including a heat insulation material containing a chlorofluorocarbon as a constituting material, a belt conveyor 2 for carrying crushed pieces of the material to be crushed, an air carrying pipe 5 provided on the terminal of the belt conveyor 2 and having a dust collector 7 as an air supply force and air ducts 6a and 6b connected with the air carrying pipe 5 and having the air supply source same as that of the air carrying pipe 5 and fractionating lightweight materials such as a heat insulation material and others recovered by the air carrying pipe 5 from middleweight materials. An electrostatic attraction device 10 having an electrode with two conductive plates or more insulated by the insulation material and coated with a film of high specific permittivity formed on the surface and also having a device for applying the direct current voltage to the conductive plates of the electrode is provided on the upper section of the belt conveyor 2 in the vicinity of the air carrying pipe 5.