Developing device including seal and image forming apparatus

A developing device comprising:

• a toner bearer;
• a layer-thickness regulating member including:
• a regulating portion to press against a surface of the toner bearer to regulate a layer thickness of toner on the toner bearer;
• and
• a projecting portion at a back side of the regulating portion:
• a seal holding surface opposite an end surface of the toner bearer;
• and
• a seal between the end surface of the toner bearer and the seal holding surface,
• wherein a part of the projecting portion opposite the end surface of the toner bearer is interposed between the seal and the end surface of the toner bearer,
• wherein the seal holding surface has a convex portion at a position opposite at least one of an upstream adjacent portion or a downstream adjacent portion adjacent to the part of the projecting portion in a surface movement direction of the toner bearer,
• wherein the seal has an adhesive layer holding the seal on the seal holding surface, and
• wherein the adhesive layer is disposed in an area of the seal other than a position opposite the part of the projecting portion and positions opposite the upstream adjacent portion and the downstream adjacent portion adjacent to the part of the projecting portion in the surface movement direction of the toner bearer.