To surely classify plastics pieces according to polarity and an electrically charged amount.

A frictionally electrical charging container 19 frictionally charging different kinds of crushed plastic pieces 16 is installed, and a classification section 21 for classifying plastic pieces 16 according to polarity and electrically charged amount is installed below the same, and the circumferential surface of a rotary drum 3 of the classification section 21 is formed of a specified plastic piece 16 of the plastic pieces 16. Since the specified plastic friction member 25 is installed so as to charge the rotary drum 23 with a polarity opposite to the specified plastic pieces, the fixed plastics 16 charged in the frictionally electrical charging container 19 repels the rotary drum 23 to be recovered to the first recovering part 28, and other plastic pieces are attracted on the circumferential surface of the rotary drum 23 to the second recovering part 29 surely.