To provide a developing device capable of reducing the irregularity of development density even when a rotation shaft for rotating a developer carrier falls down.

The developing device has the rotation shaft 205 disposed on a cylindrical development sleeve 202. A gear 301 is attached by inserting an end part of the rotation shaft 205 into a hole. The falling direction of the rotation shaft 205 and the development surface (photoreceptor 210 side) are located opposite each other. The gear 301 is off-centered to the falling direction side of the rotation shaft 205 with respect to the rotation shaft 205. The eccentricity is materialized via a spacer 303 to the falling direction side of the rotation shaft 205 between the rotation shaft 205 and the gear 301 in the hole.