PURPOSE: To prevent toner from being condensed and to improve the quality of printing by providing a toner supply blade which is provided to a toner hopper to feed the toner to a pressure releasing area and a stirring blade which is provided in the pressure releasing area to feed the toner to a developing sleeve.

CONSTITUTION: The toner stored in the toner hopper 6 is fed to the pressure releasing area 4 by the toner supply blade 7 in the toner hopper 6 and fed to the developing sleeve 3 by the stirring blade 5. Then, a toner layer is formed on the developing sleeve 3. The toner layer is made uniform by a doctor blade 2 and the toner is carried to a latent image carrier. Then, the rotating speed of the stirring blade 5 and the toner supply blade 7 is selected so that the pressure releasing area 4 is not filled up by the toner. Therefore, the pressure generated by the toner in the toner hopper 6 is not directly added to the neighborhood where the toner is regulated. Thus, the toner is prevented from being condensed and the quality of the printing is improved.