A developing cartridge includes: a casing; a developing roller rotatable about an axis extending in a first direction; a first agitator; an agitator gear; a first protrusion; a developing memory; a first electrical contact surface; and a first holder holding the first electrical contact surface. The agitator gear includes a large diameter gear and a small diameter gear positioned between the large diameter gear and the casing in the first direction. The first protrusion protrudes outward from one end of the casing in the first direction, and is positioned between the casing and the large diameter gear in the first direction. The first protrusion is positioned away from the small diameter gear. The first holder is positioned farther from the first protrusion than the large diameter gear is in the first direction. The first holder and the first electrical contact surface are movable relative to the casing.