A developing device includes a developing roller that supplies developer, a developing case that supports the developing roller, a toner cartridge that houses the developer and is attachable to and detachable from the developing case in a direction perpendicular to a longitudinal direction of the developing roller, an abutting member that is swingably provided on the developing case and is abuttable against the toner cartridge from a downstream side in a direction along which the toner cartridge is detached from the developing case, an operating member that is swingably provided on the toner cartridge, and an interlocking member that swings the abutting member between an abutting position and a canceling position, the interlocking member swinging in conjunction with a swinging operation of the operating member, and the toner cartridge being detachable from the developing case when the interlocking member is in the second position.