Developing cartridge including shaft and cam having cam surface

A developing cartridge comprising:

• a casing configured to accommodate developer therein;
• a developing roller rotatable about a first axis extending in a first direction, the developing roller having an outer circumferential surface including one end portion and another end portion in a second direction, the one end portion being exposed to an outside of the casing, the another end portion being positioned inside the casing;
• a shaft extending along a second axis extending in the first direction, the shaft being movable in the first direction relative to the casing and the developing roller, the shaft being movable in the second direction together with the casing and the developing roller, the shaft having one end portion and another end portion in the first direction;
• and
• a first inclined surface positioned at the one end portion of the shaft in the first direction and movable together with the shaft, the first inclined surface being inclined relative to the first direction such that a distance between the shaft and the first inclined surface in a radial direction of the shaft increases in a direction from the one end portion of the shaft in the first direction to the another end portion of the shaft in the first direction, the radial direction of the shaft being the second direction.