Patent ID: 8909099

Claim:
An image forming apparatus, comprising: a developing device having a developer bearing member that is disposed so as to be opposed to an image bearing member on which an electrostatic latent image is formed and, at a region thereof opposed to the image bearing member, supplies a developer to the image bearing member; a support frame that supports the developing device and is capable of disposing the developing device selectively at a mounting/demounting position where the developer bearing member is separated from the image bearing member and at a developing position where a developer can be supplied to the image bearing member; a developer supply mechanism that supplies a developer to the developing device; and a shutter member that is fitted around a connection portion of the developer supply mechanism at which the developer supply mechanism is connected to the developing device, and opens a replenishment port formed at the connection portion in tandem with movement of the developing device from the mounting/demounting position to the developing position and closes the replenishment port in tandem with movement of the developing device from the developing position to the mounting/demounting position, where a direction in which the developing device is moved, is different from a direction in which the: shutter member performs the opening/closing of the replenishment port, wherein the shutter member is a cylindrical member into which the connection portion is rotatably inserted and that has an opening portion formed on an outer peripheral surface thereof at a position that is to coincide with a position of the replenishment port, the developing device has a guide portion that has a substantially oval section and into which the shutter member is inserted, and the developing device is moved to and fro between the mounting/demounting position and the developing position, so that the shutter member is relatively and horizontally moved while rotating within the guide portion, and thus opens/closes the replenishment port.