Patent ID: 8693928

Claim:
A development device comprising: an image carrier configured to develop an electrostatic latent image by using a developer; a development member configured to supply the developer to the image carrier; a developer supply member configured to supply the developer onto a surface of the development member; and a developer restriction member including a contact portion configured to form a developer layer on the surface of the development member while being in contact with the surface, wherein a curvature radius R [mm] of the contact portion of the developer restriction member is 0.17 [mm] to 0.28 [mm], both inclusive, and an ASKER F hardness [°] of the developer supply member is 181.82 ×R+ 9.09 ≦F≦− 250 ×R+ 130, wherein the developer supply member has an almost columnar shape, and the developer supply member satisfies 0.962≦L 1 /L 2 ≦1, where L 1 is an outer diameter of the developer supply member in an portion near an end in a longitudinal direction, and L 2 is an outer diameter thereof in a center portion in the longitudinal direction.