To solve the problem that a technique by which one kind of plastic can be selected with high selection precision and by a simple method is desired to be developed since newly developed examples of an electrostatic sorting method is few in regard to a method for electrostatically sorting a plural number of materials such as plastics.

The electrostatic sorting method of this invention is constituted by triboelectrifying a mixture composed of a plural number of materials of different triboelectrification series and naturally dropping the mixture in an electric field. In particular, triboelectrification using a cyclone is preferable and separation efficiency is improved by covering an inwall of the cyclone with an intermediate material among the triboelectrification series of the material to be separated. Further charging efficiency is improved and continuous treatment is also attained by making length of the cylindrical part of the cyclone at or more than twice the length of the cone part.