Developing cartridge, side cover mounting method and electrophotographic image forming apparatus

An electrophotographic image forming apparatus for forming an image on a recording material, and to which a developing cartridge is detachably mountable, comprising:

• (i) an electrophotographic photosensitive drum;
• and
• (ii) a mounting portion configured and positioned to detachably mount the developing cartridge, which includes a cartridge frame, a developing roller configured and positioned to develop an electrostatic latent image formed on said electrophotographic photosensitive drum, a one-end frame groove provided at one longitudinal end of the cartridge frame, a one-end bearing member configured and positioned to rotatably support a one-end shaft provided at one longitudinal end of the developing roller extending in a longitudinal direction of the cartridge frame, a one-end bearing member cylinder, which is provided on the one-end bearing member and which has an outer surface engaged with an inner surface of the one-end frame groove, a one-end side cover provided at one longitudinal end of the cartridge frame and covering the one-end bearing member, and a one-end side cover projection provided on an inside of the one-end side cover and engaged with an inner surface of the one-end bearing member cylinder, which is engaged with the inner surface of the one-end frame groove.