A developing cartridge comprising: a developing roller rotatable about an axis extending in an axial direction; a coupling rotatable about an axis extending in the axial direction; a first gear rotatable about a first axis extending in the axial direction upon receiving driving force from the coupling; a second gear rotatable about a second axis extending in the axial direction and rotatable about the first axis between a first position and second position while being in meshing engagement with the first gear; a third gear rotatable upon receiving driving force from the first gear; and a cam configured to move the second gear to the first position and to the second position, the cam being rotatable about a third axis extending in the axial direction by the rotation of the third gear; wherein the third gear comprises; a gear teeth portion configured to receive the driving force from the first gear; a first toothless portion configured to shut off the driving force from the first gear when the first toothless portion faces the first gear; and a second toothless portion provided at a position different from a position of the first toothless portion in a rotational direction of the third gear, the second toothless portion being configured to shut off the driving force from the first gear when the second toothless portion faces the first gear, the gear teeth portion being positioned between the first toothless portion and the second toothless portion in the rotational direction of the third gear; the cartridge being configured such that the cam positions the second gear to the first position when the first toothless portion faces the first gear, and the cam positions the second gear to the second position which is positioned closer to the third axis than the first position is to the third axis when the second toothless portion faces the first gear. a developing roller rotatable about an axis extending in an axial direction; a coupling rotatable about an axis extending in the axial direction; a first gear rotatable about a first axis extending in the axial direction upon receiving driving force from the coupling; a second gear rotatable about a second axis extending in the axial direction and rotatable about the first axis between a first position and second position while being in meshing engagement with the first gear; a third gear rotatable upon receiving driving force from the first gear; and a cam configured to move the second gear to the first position and to the second position, the cam being rotatable about a third axis extending in the axial direction by the rotation of the third gear; wherein the third gear comprises; a gear teeth portion configured to receive the driving force from the first gear; a first toothless portion configured to shut off the driving force from the first gear when the first toothless portion faces the first gear; and a second toothless portion provided at a position different from a position of the first toothless portion in a rotational direction of the third gear, the second toothless portion being configured to shut off the driving force from the first gear when the second toothless portion faces the first gear, the gear teeth portion being positioned between the first toothless portion and the second toothless portion in the rotational direction of the third gear; the cartridge being configured such that the cam positions the second gear to the first position when the first toothless portion faces the first gear, and the cam positions the second gear to the second position which is positioned closer to the third axis than the first position is to the third axis when the second toothless portion faces the first gear. a first toothless portion configured to shut off the driving force from the first gear when the first toothless portion faces the first gear; and a second toothless portion provided at a position different from a position of the first toothless portion in a rotational direction of the third gear, the second toothless portion being configured to shut off the driving force from the first gear when the second toothless portion faces the first gear, the gear teeth portion being positioned between the first toothless portion and the second toothless portion in the rotational direction of the third gear; the cartridge being configured such that the cam positions the second gear to the first position when the first toothless portion faces the first gear, and the cam positions the second gear to the second position which is positioned closer to the third axis than the first position is to the third axis when the second toothless portion faces the first gear.