PURPOSE: To effectively remove the remaining fine developer particles by disposing a magnet in proximity to the side face opposite from the image forming surface of a dielectric layer, acting magnetic force upon the fine magnetic material particles of the residual developer and attracting and removing these by vacuum suction means.

CONSTITUTION: A blade 9, a fur brush 10 and vacuum suction means 11 are disposed in proximity to the latent image forming surface of a dielectric layer 2, and the residual fine magnetic particles moving along with the movement of the dielectric layer 2 are attracted and removed by the suction means while the brush 10 is being rotated. A magnet 8 is provided in proximity to the surface on the side opposite from the latent image forming surface of this dielectric layer to act the magnetic force by this magnet upon the fine magnetic material particles 7 to hinder their movement, thereby giving the effect equal to that when the moving speed of the dielectric layer 2 becomes low. This makes it possible to enhance the suction removing effect by the suction means 11 and to effciently remove the fine developer particles.