A developing cartridge includes a casing having a toner chamber, a feeding roller installed within the toner chamber, a developing roller supplied with a toner from the feeding roller, and a sealing film interposed between the developing roller and the feeding roller. The sealing film blocks a movement of the toner toward a gap between the developing roller and a bottom of the toner chamber, so that the toner does not leak out through the gap between the developing roller and the bottom of the toner chamber.