A developing cartridge is provided. The developing cartridge includes a first frame and a second frame and a layer thickness regulating member. The first frame and the second frame include a first welding surface formed at a periphery of the developer accommodating part correspondingly to a developer accommodating part; and a second welding surface extending continuously from the first welding surface correspondingly to a roller support part. The first welding surface extends in a direction orthogonal to an overlapping direction of the first frame and the second frame. The second welding surface extends to be inclined toward a side of the first frame in the overlapping direction as extending toward the developing roller. The layer thickness regulating member is provided to cover the second welding surface from a side of the second frame in the overlapping direction.