A developing unit and a developer stirring and transporting method are provided that enable smooth discharge of a developer in the developing unit without being affected by the inclination of the developing unit. A developing unit 10 has a developing roller 12, a housing unit 16 configured to house a developer and having in its sidewall a discharge port 14 which discharges overflowing developer, a stirring and transporting member 20 configured to stir and transport the developer along a passage 18 formed in the housing unit 16, and a deposit structure unit 22 provided in the passage 18 and configured to raise the height position of a bottom surface 18a part of the passage 18 corresponding at least to the discharge port 14 to a position higher than the other areas of the passage 18, and thereby deposit the developer near the discharge port 14.