PURPOSE: To perform powder classification, by a method wherein a fine powder comprising different components is collided with the vessel wall and the rotary wall in a rotary blade shaped charging apparatus to generate friction charge and electrostatic separation is performed corresponding to a charge amount.

CONSTITUTION: A comminuted gaseous mixture is guided to a charging chamber 23 formed by arranging a plurality of revolving stream generating cylinders 23' to a spacer plate 232. Each cylinder 231 is formed by partitioning the same by a twisted partition plate 233. Because the gaseous mixture guided to this charging chamber 23 generates violet revolution, powder particles repeat violet collision with the inner wall of the cylinder 231 by receiving centrifugal force and sent to an electrostatic separation chamber while charged with friction charge. In this electrostatic separation chamber, two flat electrodes are arranged in parallel relation to the advance direction of the gas stream so as to be exposed to the gas stream, DC high voltage is applid to the flat electrodes and the charged powder particles are collected corresponding to the polarities thereof and the charge amounts thereof by a negative and a positive electrodes.