The toner moves as shown in the above drawing. The toner agitator [A] mixes the toner so that it is transported evenly to the mixing rollers. The upper mixing roller [B] moves toner to the center, then the lower mixing roller [C] moves toner to the right and left sides. Finally, the toner supply roller [D] supplies toner to the development roller. This mixing mechanism prevents toner hardening and uneven image density in the outputs.