Patent ID: 8320793

Claim:
A development device comprising: a casing configured to accommodate development agent, the casing comprising a first frame and a second frame, the first frame having an opened first side face and a second side face adjacent to the first side face, the second side face being formed with an opening, the second frame being connected with the first frame so as to seal the first side face of the first frame; a developing member rotatably supported, in the opening, by the casing, the developing member being configured to hold development agent on an outer circumferential surface thereof; a regulating member configured to contact the outer circumferential surface of the developing member so as to regulate a layer thickness of the development agent on the outer circumferential surface of the developing member; two attachment surfaces provided to the second side face of the first frame, the attachment surfaces being disposed at both outsides of the opening in a first direction parallel to a rotational axis of the developing member, respectively, the attachment surfaces being configured such that the regulating member is attached thereto; a facing surface provided to the second frame, the facing surface being disposed between the attachment surfaces, in a predetermined plane including the attachment surfaces, the facing surface being configured to face a portion of the regulating member between the attachment surfaces; and a seal member disposed between the regulating member and the predetermined plane including the attachment surfaces and the facing surface, the seal member being configured to seal first gaps each of which is formed in the first direction between the facing surface and one of the attachment surfaces.