A toner container is elongated. A first rotating member is rotatably provided in a first toner storage portion and extends in a depth direction of a container main body. A first drive input portion is provided at an end of a first rotation shaft included in the first rotating member and configured to receive a driving force. A second rotating member rotatably provided in a second toner storage portion and extends in the depth direction. A second drive input portion is provided at an end of a second rotation shaft included in the second rotating member and configured to receive a driving force. The container main body includes a plate-like coupling member coupling a first housing of the first toner storage portion with a second housing of the second toner storage portion.

A developing unit, which is attachable to and detachable from a photosensitive member unit, includes: a developing roller; a housing in which a holding space that holds toner is formed; and a pressing receiving portion that receives pressing force from a pressing member. The housing includes a first bottom portion that projects toward an outer side of the holding space, and a second bottom portion that projects toward the outer side of the holding space, in a state in use. When viewed in a direction of a rotation axis of the developing roller, at least part of the pressing receiving portion is located in a space surrounded by the first bottom portion, the second bottom portion, and a tangent line tangent to both an outer wall of the first bottom portion and an outer wall of the second bottom portion.

An injection inlet for injecting elastomer into a gap between frames and a seal member, a storage portion in which the elastomer flowing out of the injection inlet is stored, and a protruding portion that protrudes toward a conveyance path of a recording medium to which a developer image is transferred, are provided in the frames, and the protruding portion protrudes toward the conveyance path further than the storage portion exposed to the conveyance path.

An opposing surface of a partition opposing a first conveyance screw includes an arc-shaped guide portion for guiding conveyance of developer at least on an upstream side in a first conveyance direction of the first conveyance screw. The guide portion is extended from a bottom portion of a first chamber opposing the first conveyance screw and formed along an outer periphery of the first conveyance screw. As seen in a cross section orthogonal to a rotation axis of the first conveyance screw, the opposing surface of the partition within a predetermined area includes the guide portion over an angle of 30% or more of the predetermined area in a direction of rotation of the first conveyance screw.

A developing device includes: a first transport member and a second transport member that are disposed in a first transport path and a second transport path provided at an upper side and a lower side in a gravitational direction and that transport a developer. The developing device also includes an ejecting path that is provided in the first transport path disposed at the upper side in the gravitational direction and that ejects an excess developer. The developing device includes a reverse helical section that is disposed in front of a support that supports the second transport member. The reverse helical section helically extends in a reverse direction relative to a helical section provided for circulating the developer, the developer being transported to the ejecting path by the reverse helical section.

An image forming apparatus includes an apparatus body and a detachable unit to be attached to the apparatus body in an attachment direction and detached from the apparatus body in a detachment direction. The detachable unit includes a rotary body and a unit drive gear. The apparatus body includes an apparatus-body drive gear to engage with the unit drive gear of the detachable unit attached in the apparatus body, at an engageable position on a downstream side of the apparatus-body drive gear in the attachment direction. One or each of the unit drive gear and the apparatus-body drive gear moves to a retracted position at which the one or each of the unit drive gear and the apparatus-body drive gear does not engage with the other of the unit drive gear and the apparatus-body drive gear and does not interfere with attachment and detachment operations of the detachable unit.

A toner cartridge include a convex portion and a conveyance drive gear. There is a protrusion which protrudes from the center of the conveyance drive gear. Further, there is a hole at a rear side of the convex portion. The protrusion is to be inserted into the hole which is at the rear side of the convex portion.

A developing device includes a developing container, a detecting unit including a base portion and a detecting portion, a feeding path, a feeding screw, and a recessed portion provided on a side wall of the developing container. The recessed portion is disposed so as to project toward the feeding screw in the feeding path. The side wall includes a projected region projected toward the screw portion in the feeding path by the recessed portion and a region other than the projected region. The feeding screw includes a first screw portion opposing the projected region and a second screw portion opposing the region other than the projected region. The first screw portion includes a rotation shaft which includes a portion having a shaft diameter smaller than a shaft diameter of a rotation shaft of the second screw portion.

A conveyance mechanism which includes a rotation shaft extending in a direction along a first direction connecting first and second discharge ports that is rotatable with a rotation axis extending in the first direction. Wherein, a first rotation conveyance unit is disposed on the rotation shaft, and is rotatable together with the rotation shaft, conveys developer toward the first discharge port, and a second rotation conveyance unit is disposed on the rotation shaft, and is rotatable together with the rotation shaft, conveys developer toward the second discharge port. The second rotation conveyance unit is configured to provide a larger amount of conveyance than the first rotation conveyance unit.

A developer cartridge may include: a first gear having a small-diameter gear portion and a large-diameter gear portion; and a second gear including: a first columnar portion centered on a second axis; a second columnar portion having a smaller diameter than the first columnar portion; a first engagement portion extending along a portion of a peripheral surface of the first columnar portion and engageable with the small-diameter gear portion; a second engagement portion extending along a portion of a peripheral surface of the second columnar portion and positioned closer to a housing than the first engagement portion in an axial direction and engageable with the large-diameter gear portion; and a protruding portion protruding in the axial direction and rotatable together with the first engagement portion and the second engagement portion. The second engagement portion may engage the large-diameter gear portion after the first engagement portion engages the small-diameter gear portion.