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 (right 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 (51, 115) that is attached to the housing and that has a first developing supporting portion (54, 117) and a driving-force-receiving-member supporting portion (56, 123), the first developing supporting portion (54, 117) being configured to rotatably support the first part of the rotational shaft, the driving-force-receiving-member supporting portion (56, 123) being configured to rotatably support the driving-force-receiving member; and a second supporting member (81, 116) that is attached to the housing and that has a second developing supporting portion (84, 117) and a detection-rotational-body supporting portion (88, 124), the second developing supporting portion (84, 117) being configured to rotatably support the second part of the rotational shaft, the detection-rotational-body supporting portion (88, 124) being configured to rotatably support the detection rotational body, characterized in that the second supporting member (81, 116) is configured to be electrically conductive, and wherein the detection-rotational-body supporting portion (88, 124) is configured to be supplied with electric power from the outside of the developing cartridge. 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 (right 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 (51, 115) that is attached to the housing and that has a first developing supporting portion (54, 117) and a driving-force-receiving-member supporting portion (56, 123), the first developing supporting portion (54, 117) being configured to rotatably support the first part of the rotational shaft, the driving-force-receiving-member supporting portion (56, 123) being configured to rotatably support the driving-force-receiving member; and a second supporting member (81, 116) that is attached to the housing and that has a second developing supporting portion (84, 117) and a detection-rotational-body supporting portion (88, 124), the second developing supporting portion (84, 117) being configured to rotatably support the second part of the rotational shaft, the detection-rotational-body supporting portion (88, 124) being configured to rotatably support the detection rotational body, characterized in that the second supporting member (81, 116) is configured to be electrically conductive, and wherein the detection-rotational-body supporting portion (88, 124) is configured to be supplied with electric power from the outside of the developing cartridge.