DEVELOPING DEVICE

PROBLEM TO BE SOLVED: To maintain a toner layer on a developing roller to be constant over a long period. SOLUTION: A toner layer regulation member 40 is formed of metallic material so that wear is prevented, and then a state where the toner layer is made thin caused by the wear of the toner layer regulation member 40 is avoided. The surface roughness of a contact surface 39 with the developing roller 37 of the member 40 is set to be 1/3 or 3/4 of the average particle size of toner, so that the smoothness of the surface 39 is improved by filling the particles of the toner on the rough surface of the surface 39. In this case a phenomenon that the particles of the toner clogged on the rough surface of the surface 39 escape from the rough surface of the surface 39 by the pressure of the particles of succeeding toner before melt-sticking by heat and the particles of the succeeding toner are filled on the rough surface of the surface 39 is repeated, so that the smoothness of the surface 39 is always maintained to be excellent, the toner layer on the developing roller 37 is made constant over the long period and image quality is improved while avoiding the state where the particles of the toner are melt-stuck on the surface 39.