Patent ID: 8190066

Claim:
A developing unit comprising: a developer cartridge comprising: an outside frame; an inside frame that comprises a first opening opened toward outside of the inside frame and is movable between a first opening position where the first opening is opened and a first closing position where the first opening is closed by the outside frame; and a first seal disposed around the first opening on the inside frame; a housing that comprises a cartridge holding part for holding the developer cartridge and is configured to hold a developer holding member; and a capturing member which is provided on the cartridge holding part, which has a developer capturing force greater than that of the first seal, and which is slide contactable with the first seal when the inside frame moves from the first opening position to the first closing position, wherein the first seal comprises a first contact portion that is contactable with the capturing member, wherein the capturing member comprises a second contact portion that is contactable with the first seal, and wherein a surface roughness of the second contact portion is greater than a surface roughness of the first contact portion on the basis of a ten-point average roughness.