To improve the sorting accuracy of an electrostatic sorting device for sorting materials to be sorted according to electrified conditions thereof by providing a preliminary triboelectrifying device for giving friction to the materials to be sorted in advance to electrify it and a triboelectrifying device for further giving friction to the preelectrified materials to be electrified to electrify it.

From the polyvinyl chloride lining applied to a transportation pipe 11 and a cyclone 14 constituting a preliminary triboelectrifying device 1, friction is given to materials to be sorted in advance to electrify it. After that, by a reciprocating friction generator 20 by which a box body 22 constituting a triboelectrifying device 2 is reciprocated, friction is further given to all the materials to be sorted to electrify it. Next, the materials to be sorted thus electrified are sucked by a pair of electrodes 41, 42 constituting an electrostatic sorting device 4 and having the shape of a truncated chevron whose opposite spacing is gradually enlarged according to the electrified conditions of the materials to be sorted to guide them along the inclined electrodes. Then, the materials to be sorted are separated and made to fall from the outlet side of the electrodes having the shape of a truncated chevron whose spacing is largest to undergo sorting.