Developing Unit

A developing unit comprising:

• a housing configured to accommodate therein a developing agent;
• a developing roller disposed in the housing and configured to rotate on a first axial line;
• and
• a seal disposed in the housing and contacting an outer peripheral surface of the developing roller,
• wherein the seal comprises:
• a first part disposed inward in an axial line direction of the developing roller and contacting the outer peripheral surface of the developing roller;
• and
• a second part contacting an outer edge of the first part in the axial line direction, disposed outward from the first part in the axial line direction and contacting the outer peripheral surface of the developing roller,
• wherein the first part has a contact surface contacting the developing roller and a plurality of first grooves each of which is recessed from the contact surface and extends along the contact surface, and
• wherein the plurality of first grooves extends from outward to inward in the axial line direction, as the plurality of first grooves extends from upstream to downstream in a rotational direction of the developing roller.