A developing device includes first and second developer carriers facing each other in a facing region, a regulating member that regulates a layer thickness of developer, and a separation member. The first and second developer carriers respectively include first and second magnetic members that are respectively magnetized with first and second facing magnetic poles having opposite polarities. The separation member separates the developer so that the developer is supplied toward the first and second developer carriers. The separation member is disposed such that distances between the separation member and the first and second developer carriers are the smallest in a region in which a magnitude of a combined magnetic field of the first and second magnetic poles locally decreases as compared with a case where at least one of the first and second developer carriers is independently disposed due to interaction between the first and second facing magnetic poles.