A development device includes a development mechanism, an agitation unit connected to the development mechanism, to agitate and mix together the developer collected from the development mechanism and fresh toner, and a transport member to transport the agitated developer from the agitation unit to the development portion. The development mechanism includes a developer carrier to carry the developer, multiple supply ports disposed at different positions in an axial direction of the developer carrier, through which the agitated developer is supplied to the development mechanism, a discharge port, a developer supply member to supply the developer to the developer carrier while transporting the developer in the direction parallel to the axial direction of the developer carrier, and a developer collection member to collect the developer from the developer carrier.