Developing cartridge provided with receiving member capable of efficiently transmitting drive force to developer carrier

A developing cartridge comprising:

• a casing configured to accommodate a developer therein and including a support portion;
• a developing roller having a rotation axis extending in an axial direction, the developing roller having an axial end portion in the axial direction;
• a developing gear supported at the axial end portion of the developing roller;
• and
• a receiving member configured to receive a drive force from an external drive source to transmit the drive force to the developing roller, the receiving member having a cylindrical configuration with an axis extending parallel to the rotation axis of the developing roller and being configured to rotate about the axis, the support portion being configured to support the receiving member such that the receiving member is capable of rotating relative to the support portion, the receiving member comprising:
• a receiving portion extending in a radial direction of the receiving member and configured to receive the drive force from the external drive source, the receiving portion having an outer edge in the radial direction;
• a gear portion configured to transmit the drive force received by the receiving portion to the developing roller, the gear portion defining an outer circumferential edge of the receiving member and meshedly engaging the developing gear;
• and
• a fitting portion positioned inward of the gear portion in the radial direction and having a cylindrical configuration fitted with the support portion so as to be capable of rotating relative to the support portion, the outer edge of the receiving portion being positioned inward of the gear portion in the radial direction and outward of the fitting portion in the radial direction.