A developing device includes a developing roller. The developing roller includes a magnetic roller configured to have multiple magnetic poles in a circumferential direction thereof and a roller-shaped developing sleeve sheathed on the magnetic roller, and supplies magnetic toner to a photosensitive drum. Further, the developing sleeve is configured such that a surface of an image region thereof, which is located in an intermediate portion thereof in a rotation axis direction thereof and which supplies the magnetic toner to the photosensitive drum, is coated with a non-magnetic material, and such that surfaces of non-image regions thereof, which are located at opposite ends thereof in the rotation axis direction and which supply no magnetic toner to the photosensitive drum, are coated with a magnetic material.