Developing cartridge including developing roller and coupling

A developing cartridge, comprising:

• a housing that is configured to accommodate developing material therein and to have a first end and a second end along a predetermined direction, a from-first-to-second direction being defined along the predetermined direction as being directed from the first end to the second end, a from-second-to-first direction being defined along the predetermined direction as being directed from the second end to the first end;
• a developing roller having a rotational shaft that extends in the predetermined direction and that has a first part and a second part, the first part and the second part being apart from each other in the predetermined direction, the second part being located on a downstream side relative to the first part in the from-first-to-second direction;
• a driving-force-receiving member that is configured to receive driving force from an outside of the developing cartridge;
• a detection rotational body that is configured to be detected by a detecting unit that is provided outside of the developing cartridge;
• a first supporting member that is attached to the housing and that has a first developing supporting portion and a driving-force-receiving-member supporting portion, the first developing supporting portion being configured to rotatably support the first part of the rotational shaft, the driving-force-receiving-member supporting portion being configured to rotatably support the driving-force-receiving member;
• and
• a second supporting member that is attached to the housing and that has a second developing supporting portion and a detection-rotational-body supporting portion, the second developing supporting portion being configured to rotatably support the second part of the rotational shaft, the detection-rotational-body supporting portion being configured to rotatably support the detection rotational body.