A development cartridge comprising: a developing roller; a developer housing to receive a developer, the developer housing comprising: a developing chamber to have the developing roller in the developing chamber and extending in a longitudinal direction of the developing roller, an agitating chamber located parallel to the developing chamber, a partition wall to separate the developing chamber from the agitating chamber, the partition wall having a first communication hole and a second communication hole respectively formed at both end portions of the partition wall in the longitudinal direction, through which the developing chamber and the agitating chamber are to communicate through, a developer inlet through which the developer is injectable into the developer housing, for the developer housing to receive the developer, the developer inlet formed in the developer housing at a position corresponding to the first communication hole or the second communication hole, the developer inlet closeable with a cap, and characterized in that the cap has a protrusion protruding into a corresponding communication hole from among the first and second communication holes (231, 232), extending in the longitudinal direction, and to limit an area of an opening of the corresponding communication hole. a developing roller; a developer housing to receive a developer, the developer housing comprising: a developing chamber to have the developing roller in the developing chamber and extending in a longitudinal direction of the developing roller, an agitating chamber located parallel to the developing chamber, a partition wall to separate the developing chamber from the agitating chamber, the partition wall having a first communication hole and a second communication hole respectively formed at both end portions of the partition wall in the longitudinal direction, through which the developing chamber and the agitating chamber are to communicate through, a developer inlet through which the developer is injectable into the developer housing, for the developer housing to receive the developer, the developer inlet formed in the developer housing at a position corresponding to the first communication hole or the second communication hole, the developer inlet closeable with a cap, and characterized in that the cap has a protrusion protruding into a corresponding communication hole from among the first and second communication holes (231, 232), extending in the longitudinal direction, and to limit an area of an opening of the corresponding communication hole. a developing chamber to have the developing roller in the developing chamber and extending in a longitudinal direction of the developing roller, an agitating chamber located parallel to the developing chamber, a partition wall to separate the developing chamber from the agitating chamber, the partition wall having a first communication hole and a second communication hole respectively formed at both end portions of the partition wall in the longitudinal direction, through which the developing chamber and the agitating chamber are to communicate through, a developer inlet through which the developer is injectable into the developer housing, for the developer housing to receive the developer, the developer inlet formed in the developer housing at a position corresponding to the first communication hole or the second communication hole, the developer inlet closeable with a cap, and characterized in that the cap has a protrusion protruding into a corresponding communication hole from among the first and second communication holes (231, 232), extending in the longitudinal direction, and to limit an area of an opening of the corresponding communication hole.