PURPOSE: To enable the defective particles in the magnetic toner to be surely removed by providing a mechanism of magnetically sucking the magnetic toner by a magnetical conveying means and conveying the same into the magnetic field of a generating means of electrostatic attraction force opposite from its attraction force.

CONSTITUTION: The magnetic toner 9 to be used for developing etc. of latent images is charged into a toner replenishing vessel 3. An insulating drum 1 is beforehand charged by an electric charging device 10. A nonmagnetic sleeve 4 and a magnet roll 5 are relatively rotated to draw out the magnetic toner 9 and convey the same in the sleeve 4. If in this case the electrostatic attraction force by the static charge on the insulating drum 1 and the magnetic attraction force by the magnet roll 5 are balanced, the defective particles in the toner are stuck on the insulating drum 1, but the normal particles are conveyed on the sleeve 4 and are recovered into a recovery box 7 by a scrapping plate 6. The defective particles stuck on the insulating drum 1 are decreased of electric charge by a destaticization device 8 and are thereby removed from the drum, after which they are recovered into a recovery box 7'.