To effectively electrify plastic fragments to be classified before feeding them into an electrostatic selector to separate them according to their kinds by the electrostatic selector and improve selection accuracy.

A triboelectrifying device is constituted of an electrifying tube 3 made of a resin material to be subjected to friction wound in a spiral in which a feeding port 3a for plastic fragments is formed at one end and also a discharge port 3b for plastic fragments is formed at the other end, a pneumatic pump 5 for pneumatically sending plastic fragments in the electrifying tube 3, and a turning blade 6 made of a resin material to be subjected to friction arranged in the electrifying tube 3 for turning and moving plastic fragments to bring them into slidable contact with the material to be subjected to friction.