Developing Device and Image Forming Apparatus

A developing device comprising:

• a developing roller that includes a roller body portion which carries a non-magnetic monocomponent developer on an outer peripheral surface thereof;
• a casing that includes:
• a developer storage unit which has a boxed shape and stores the developer therein;
• a roller supporting unit which protrudes in a direction perpendicular to a central axis direction of the developing roller from the developer storage unit and rotatably supports both end portions of the developing roller outside the roller body portion in the central axis direction;
• and
• an opening which extends in a longitudinal direction along the central axis direction so as to make the developer storage unit and the roller supporting unit to communicate with each other;
• and
• a seal member that is mounted on the casing outside the opening in the central axis direction and faces an end portion of the outer peripheral surface of the roller body portion in the central axis direction, the seal member configured to rub against the end portion of the outer peripheral surface in the central axis direction when the seal member is elastically deformed by being pressed in a radial direction of the roller body portion by the roller body portion,
• wherein
• the casing includes:
• an outer projection that is provided along a moving direction of the developing roller so as to abut on an outer end portion of the seal member in the central axis direction, the outer projection protruding in a position which is inside the roller supporting unit in the central axis direction;
• and
• an inner projection that is provided along the outer projection so as to abut on an inner end portion of the seal member in the central axis direction, the inner projection protruding in a position which is outside the opening in the central axis direction.