Patent ID: 8494400

Claim:
A developing device comprising: a toner carrying member for supplying toner to an image bearing member at an opposing region opposing the image bearing member, the toner carrying member being arranged so as to be opposed to the image bearing member on which an electrostatic latent image is to be formed; a toner supply member for supplying only the toner to the toner carrying member, the toner supply member having a developer containing the toner and a carrier carried thereon; a blade for regulating an amount of the developer carried on the toner supply member; a casing for housing the toner carrying member, the toner supply member, and the blade, the casing including a wall portion opposed to the toner carrying member between the blade and the opposing region; a sheet member that is flexible, is provided on the wall portion, has a free end, forms a part of an inner wall surface of the wall portion, and is movable in a direction perpendicular to the inner wall surface; and a moving portion provided on the wall portion, for moving the sheet member, wherein the wall portion has a recessed portion recessed from the inner wall surface side formed thereon; the moving portion comprises an oval roller provided in the recessed portion; and the sheet member is arranged at a position covering the recessed portion, and moves by being pressed against a circumferential surface of the oval roller.