Abstract: A developing device which is particularly advantageous from the standpoint of avoiding leakage or scattering of toner. The developing device is additionally advantageous in allowing for a compact design while reliably supplying toner to the complete area of a photosensitive member upon which a latent image is formed. The developing device includes a toner container having an opening in a lower part thereof, through which toner falls. A magnet bar is provided below the opening, with a developing grid covering a portion of the magnet bar. The magnet bar forms a magnetic toner brush which penetrates through holes in the developing grid, with the magnetic toner brush and grid cooperating to prevent excessive toner from falling through the opening and thus preventing excessive toner from scattering outside the developing device.