A developing cartridge includes a coupling member provided adjacent to a first end of a casing. The coupling member is operatively connected to a developing roller, and the coupling member is rotatable about a rotational axis thereof. The coupling member includes (i) a cylindrical portion, (ii) a first projection at least partially positioned inside of the cylindrical portion, (iii) a second projection at least partially positioned inside of the cylindrical portion, (iv) an elastically movable projection at least partially positioned inside of the cylindrical portion, and (v) a wall extending in a direction perpendicular to the rotational axis and positioned between a second end of the casing and the first and second projections.