Patent ID: 8849154

Claim:
A developing device comprising: a developing roller longitudinally extending in a first direction; a casing configured to rotatably support both end portions of the developing roller; and a seal member that contacts an end portion of an outer peripheral surface of the developing roller in the first direction, wherein the seal member comprises: an outer side surface in the first direction, provided along a moving direction of the developing roller; an inner side surface in the first direction, provided along the moving direction of the developing roller; and a downstream side surface in the moving direction of the developing roller, and wherein the casing includes: a first projection provided along the moving direction of the developing roller so as to abut and contact the outer side surface of the seal member in the first direction; a second projection provided along the first projection so as to abut and contact the inner side surface of the seal member in the first direction, the second projection protruding in a position which is inside the first projection in the first direction; and a third projection provided along the first direction so as to abut and contact the downstream side surface of the seal member, the third projection protruding in a position which is between the first projection and the second projection in the first direction.