A developing device includes a developer-carrying member and a developer control member, a supply member, and a rotating member that are disposed opposite the developer-carrying member. The developer-carrying member accommodates a magnetic source that generates a magnetic force for carrying a developer containing magnetic particles on an outer surface thereof. The developer control member controls the thickness of a layer of the developer carried on the outer surface of the developer-carrying member. The supply member rotates to transport the developer in a rotation axis direction thereof and to supply the developer to the developer-carrying member. The rotating member is disposed at a position where the rotating member is submerged in the developer between the developer control member and the supply member and rotates to supply the developer from between the developer control member and the supply member to the supply member.