In a developing device, a developing roller has: a first rotational shaft extending in a first direction; and a first roller body covering the first rotational shaft and configured to carry developer. A supply roller has: a second rotational shaft extending in the first direction; and a second roller body covering the second rotational shaft and configured to supply the developer to the developing roller. A housing accommodates the developing roller, the supply roller, and the developer. The housing includes a first wall and a second wall opposed with each other in the first direction. The first wall is formed with a first cutout. The second wall being formed with a second cutout. The first rotational shaft and the second rotational shaft are positioned in both the first cutout and the second cutout when projected in the first direction.