A process unit comprising: a developing cartridge comprising: a casing configured to accommodate therein developing agent; a developing roller rotatable about a developing roller axis extending in a first direction, the developing roller being positioned at one end of the casing in a second direction crossing the first direction; a first agitator rotatable about an agitator axis extending in the first direction; an agitator gear positioned at one end in the first direction of the casing and rotatable about the agitator axis together with the first agitator, the agitator gear comprising: a large diameter gear; and a small diameter gear having a diameter smaller than a diameter of the large diameter gear, the small diameter gear being positioned between the large diameter gear and the casing in the first direction; a first protrusion protruding outward in the first direction from the one end in the first direction of the casing, the first protrusion being positioned between the casing and the large diameter gear in the first direction, the first protrusion being positioned away from the small diameter gear in the second direction; a developing memory; a first electrical contact surface electrically connected to the developing memory; and a first holder holding the first electrical contact surface and positioned at the one end in the first direction of the casing, the first holder being positioned farther from the first protrusion than the large diameter gear is from the first protrusion in the first direction, the first holder and the first electrical contact surface being movable relative to the casing; and a drum cartridge to which the developing cartridge is attached, the drum cartridge comprising a photosensitive drum rotatable about a drum axis extending in the first direction; a drum frame; a drum memory; and an electrical contact surface electrically connected to the drum memory, the electrical contact surface being positioned at one end of the drum frame in the first direction, wherein the first electrical contact surface of the developing cartridge is positioned between the developing roller and the electrical contact surface of the drum cartridge in the second direction. a casing configured to accommodate therein developing agent; a developing roller rotatable about a developing roller axis extending in a first direction, the developing roller being positioned at one end of the casing in a second direction crossing the first direction; a first agitator rotatable about an agitator axis extending in the first direction; an agitator gear positioned at one end in the first direction of the casing and rotatable about the agitator axis together with the first agitator, the agitator gear comprising: a large diameter gear; and a small diameter gear having a diameter smaller than a diameter of the large diameter gear, the small diameter gear being positioned between the large diameter gear and the casing in the first direction; a large diameter gear; and a small diameter gear having a diameter smaller than a diameter of the large diameter gear, the small diameter gear being positioned between the large diameter gear and the casing in the first direction; a first protrusion protruding outward in the first direction from the one end in the first direction of the casing, the first protrusion being positioned between the casing and the large diameter gear in the first direction, the first protrusion being positioned away from the small diameter gear in the second direction; a developing memory; a first electrical contact surface electrically connected to the developing memory; and a first holder holding the first electrical contact surface and positioned at the one end in the first direction of the casing, the first holder being positioned farther from the first protrusion than the large diameter gear is from the first protrusion in the first direction, the first holder and the first electrical contact surface being movable relative to the casing; and a drum cartridge to which the developing cartridge is attached, the drum cartridge comprising a photosensitive drum rotatable about a drum axis extending in the first direction; a drum frame; a drum memory; and an electrical contact surface electrically connected to the drum memory, the electrical contact surface being positioned at one end of the drum frame in the first direction, wherein the first electrical contact surface of the developing cartridge is positioned between the developing roller and the electrical contact surface of the drum cartridge in the second direction. a photosensitive drum rotatable about a drum axis extending in the first direction; a drum frame; a drum memory; and an electrical contact surface electrically connected to the drum memory, the electrical contact surface being positioned at one end of the drum frame in the first direction, wherein the first electrical contact surface of the developing cartridge is positioned between the developing roller and the electrical contact surface of the drum cartridge in the second direction.