Patent ID: 8417161

Claim:
A developing device comprising: a developing member that retains at a surface thereof a developer supplied from a developer accommodation portion, in which the developer is accommodated, and that, while rotationally moving, supplies the developer to an image-bearing body on which an electrostatic latent image is formed and develops the electrostatic latent image; a cylindrical layer thickness regulation member that is disposed to oppose the developing member, extends in a rotation axis direction of the developing member, comes up against the developer retained at the surface of the developing member, and regulates a layer thickness of the developer; and a guide surface that guides developer that has been rendered excess by the layer thickness being regulated by the layer thickness regulation member toward the developer accommodation portion, wherein the guide surface is provided such that, viewed in the rotation axis direction of the developing member, an angle that is formed between the guide surface and a tangent of the layer thickness regulation member at a point of intersection of a line of extension of the guide surface with the layer thickness regulation member is at least 90°, wherein the line of extension of the guide surface is parallel to and in contact with the guide surface, and wherein the line of extension of the guide surface extends from the point of intersection towards a direction upstream of the point of intersection when viewed along a direction parallel to the rotational direction of the developing member.