A developing cartridge detachably mountable to an electrophotographic image forming apparatus. The cartridge includes a frame, a developing roller, a frame groove, a frame projection, a bearing configured and positioned to rotatably support a developing roller shaft, a bearing cylinder, an elongated bearing opening receiving the frame projection, first and second bearing projections, first, second and third screws, a side cover covering the bearing and including a first opening engageable with the first bearing projection and a second opening engageable with the second bearing projection, and a side cover projection engageable with the bearing cylinder. The first screw secures the bearing to the frame, the second screw secures the side cover to the frame and the third screw secures the side cover to the first bearing projection.