PURPOSE: To prevent the staining of the outside part of a developing device by the scattering toner with simple constitution by providing a wind regulating plate in the predetermined position of a nonmagnetic sleeve.

CONSTITUTION: In the rotating direction of a nonmagnetic sleeve 7, a wind regulating plate 22 is provided by being extended from a developing device body 4, near the end of the earing of the developer 3 formed by the conveying magnetic pole S1 in the position next to the developing main pole N1. The developing device body 4 is partitioned from the opening part 5 near the developing main pole N1 by the earing of the developer 3 and the wind regulating plate 22. Also, an exhaust port 23 for sucking the air in which the toner near the opening part 5 is suspending based on the earing of the developer 3 moved by the rotation of the nonmagnetic sleeve 7 and the wind regulating plate 22 by the pumping action of these, and removing the air pressure developed as a result of this is provided to the developing device body 4.