A developing apparatus usable with an image forming apparatus includes a developer cartridge having an outlet through which developer is discharged, a developing cartridge, in which the developer cartridge is detachably disposed, has an inlet, through which the developer discharged from the outlet of the developer cartridge enters, and a connecting member connecting the outlet of the developer cartridge and the inlet of the developing cartridge so that the developer is supplied from the developer cartridge to the developing cartridge, wherein through the arrangement of the developer cartridge, the developing cartridge and the connecting member, the flow of developer from the developer cartridge to the developing cartridge is regulated based on the developer pressure in the developing cartridge.