To separate/recover plastic pieces correctly by using a moving means which moves the partition wall of a recovery part toward/from a drum electrode without changing the voltage of electrodes and moving it horizontally to a falling position of each plastic piece associated with the polarity and the quantity of charge of the piece.

In a recovery part 26 arranged below a separating space 22, partition walls 30, 31 are made to approach/separate from a metal drum electrode 21, and a moving means for moving the walls 30, 31 horizontally to correspond to the falling position of plastic pieces 16 so that when the separation of the plastic pieces is inaccurate, the walls 30, 31 are moved to correspond to the falling position of the plastic pieces 16 to perform the separation correctly without changing voltage from a high voltage power source apparatus 24.