To sort/separate a metallic piece and plastic pieces according to their kinds at one sorting stage.

Respective electric charges are imparted to respective components of a mixture before supply by triboelectrification. The mixture is irradiated with a negative ion from an ion discharging electrode 5 so that the electrified amount of the negatively charged plastic piece is increased and the piece is adsorbed on a rotating drum electrode 4 and the electrified amount of the positively charged plastic piece is decreased to repel the electrode 4. Metallic fine powder is brought into contact with the electrode 4 so that the metallic fine powder is electrified to have positive polarity and repel the electrode 4. In an electrostatic field S for separation, the plastic pieces are separated by their kinds by making the plastic piece having an almost neutral charge amount draw an intermediately falling locus and making the plastic piece having a negative charge draw an internally falling locus while being attracted to the electrode 4 by the electrostatic force. The metallic fine powder is separated by making it draw an externally falling locus while being attracted to an electrostatic electrode 6 side by the electrostatic force.