Patent ID: 7949282

Claim:
A developing device comprising: a housing; a developing roller that is rotatably provided in the housing and configured to carry developer; a supply roller provided in the housing, the supply roller configured to supply the developer to the developing roller; a developer cartridge that is attachable to and detachable from the housing and houses the developer; a first sealing member that is provided at both ends of a longitudinal direction of the developing roller and slidably contacts a circumferential surface of the developing roller for preventing leakage of the developer from the housing, the first sealing member including an inner end portion; a developer passage opening for passage of the developer provided in at least one of the housing and the developer cartridge; and a second sealing member provided in a vicinity of the developer passage opening for preventing leakage of the developer from the developer passage opening, at least a part of the second sealing member overlapping the first sealing member in a direction in which the developer cartridge is attachable to and detachable from the housing, wherein the second sealing member is arranged such that: an outer end portion of the second sealing member in the longitudinal direction is located outside from the inner end portion of the first sealing member in the longitudinal direction, and an inner end portion of the second sealing member in the longitudinal direction is located inside from the inner end portion of the first sealing member in the longitudinal direction, and wherein the developer cartridge is attachable to and detachable from the housing at a position opposed to the developing roller with reference to the supply roller.