A developing cartridge that can be detachably mounted to a main body of an image forming apparatus, the developing cartridge comprising: a housing having a front, back, left and right and including a developing chamber and a developer accommodating chamber that accommodates developer to be supplied to the developing chamber, wherein the developing chamber and the developer accommodating chamber are adjacent to each other; a developing roller at the back of the housing, which is provided in the developing chamber, and which includes a developing roller shaft extending in a facing direction of both sidewalls, which is the left-right direction of the housing; a supply roller, which is provided in the developing chamber in the front-back direction in front of the developing roller and which includes a supply roller shaft extending in the left-right direction of the housing, and which supplies the developer to the developing roller; a developing electrode, which is provided on an outer side of one sidewall of the housing, wherein the developing electrode is electrically connected to the developing roller shaft, and wherein the developing electrode includes a developing protrusion protruding in a direction parallel to the developing roller shaft at a position different from the developing roller shaft when seen from a side face; and a supply electrode, which is provided on the outer side of the one sidewall, wherein the supply electrode is electrically connected to the supply roller shaft, and wherein the supply electrode includes a supply protrusion protruding in a direction parallel to the supply roller shaft at a position different from the supply roller shaft when seen from the side face, characterized in that the developing chamber and the developer accommodating chamber are arranged in the front-back direction of the housing, which is a mounting direction of the developing cartridge to the main body, and the developing protrusion and the supply protrusion are arranged in an arrangement direction of the developing chamber and the developer accommodating chamber, the arrangement direction extending from the developing chamber to the developer accommodating chamber in the mounting direction, the supply protrusion comprises: a parallel surface that is parallel to the arrangement direction; and an inclined surface, which is formed contiguously with the parallel surface and extends toward the developing protrusion, and the inclined surface is inclined with respect to the parallel surface. a housing having a front, back, left and right and including a developing chamber and a developer accommodating chamber that accommodates developer to be supplied to the developing chamber, wherein the developing chamber and the developer accommodating chamber are adjacent to each other; a developing roller at the back of the housing, which is provided in the developing chamber, and which includes a developing roller shaft extending in a facing direction of both sidewalls, which is the left-right direction of the housing; a supply roller, which is provided in the developing chamber in the front-back direction in front of the developing roller and which includes a supply roller shaft extending in the left-right direction of the housing, and which supplies the developer to the developing roller; a developing electrode, which is provided on an outer side of one sidewall of the housing, wherein the developing electrode is electrically connected to the developing roller shaft, and wherein the developing electrode includes a developing protrusion protruding in a direction parallel to the developing roller shaft at a position different from the developing roller shaft when seen from a side face; and wherein the developing electrode is electrically connected to the developing roller shaft, and wherein the developing electrode includes a developing protrusion protruding in a direction parallel to the developing roller shaft at a position different from the developing roller shaft when seen from a side face; and a supply electrode, which is provided on the outer side of the one sidewall, wherein the supply electrode is electrically connected to the supply roller shaft, and wherein the supply electrode includes a supply protrusion protruding in a direction parallel to the supply roller shaft at a position different from the supply roller shaft when seen from the side face, characterized in that the developing chamber and the developer accommodating chamber are arranged in the front-back direction of the housing, which is a mounting direction of the developing cartridge to the main body, and the developing protrusion and the supply protrusion are arranged in an arrangement direction of the developing chamber and the developer accommodating chamber, the arrangement direction extending from the developing chamber to the developer accommodating chamber in the mounting direction, the supply protrusion comprises: a parallel surface that is parallel to the arrangement direction; and an inclined surface, which is formed contiguously with the parallel surface and extends toward the developing protrusion, and a parallel surface that is parallel to the arrangement direction; and an inclined surface, which is formed contiguously with the parallel surface and extends toward the developing protrusion, and the inclined surface is inclined with respect to the parallel surface.