Patent ID: 8521055

Claim:
A developing device comprising: a casing having an opening extending in a first direction; a developing roller positioned adjacent to the opening and configured to rotate about an axis extending in the first direction, the developing roller having an outer circumferential surface on which developer is carried; a thickness-regulation portion comprising a thin-plate member extending in the first direction along the opening and having a base end portion fixed to the casing and extending in the first direction and a free end portion, the thin-plate member having a lateral end extending in a second direction crossing the first direction; and a regulating portion extending in the first direction and fixed to the free end portion of the thin-plate member, the regulating portion being in contact with the outer circumferential surface of the developing roller via the developer for regulating thickness of the developer on the outer circumferential surface, the regulating portion having an end face extending in a direction crossing the first direction; a sealing member disposed on the thin-plate member and in intimate contact with the end face of the regulating portion for suppressing leakage of the developer from the casing; and a contact portion fixed on the thin-plate member at a position closer to the lateral end than the sealing member to the lateral end, the contact portion being in contact with the outer circumferential surface of the developing roller and made of a material having a hardness higher than that of the sealing member.