A toner container includes containing chambers, a shaft member, rotary members, and stirring members. The containing chambers are arrayed in a first direction and partitioned from each other. The containing chambers contain respective toners of different colors. The shaft member extends in the first direction, passes through the containing chambers, and is rotatable about a rotational axis extending in the first direction. The rotary members are disposed in the respective containing chambers and each have a through-hole extending in the first direction. The rotary members are rotatable in response to rotation of the shaft member in an inserted state of the shaft member in the through-holes. The stirring members are supported by the respective rotary members and each extend in a second direction intersecting the first direction. The stirring members are pivotable in response to rotation of the respective rotary members. The stirring members have different pivoting positions upon pivoting.

A developer accommodating unit for accommodating a developer for image formation includes a flexible container provided with an opening 35a for permitting discharge of the developer, a frame for accommodating the flexible container and for accommodating the developer to be discharged from the flexible container, and an urging member 21 for urging a developer accommodating bag toward the frame for accommodating the developer accommodating bag 16. By this, it is possible to satisfactorily effect discharge of the developer from the flexible developer accommodating bag 16.

A cartridge includes a shutter that opens and closes when the cartridge is attached and detached to a developing unit or image forming apparatus. The cartridge includes a casing having a chamber with a first opening at one end portion allowing toner to flow out of the casing. The cartridge includes a cover that covers the first opening, movable with the casing and having a second opening allowing toner to flow out of the cover. The shutter is located at the one end portion and has a protrusion further from the one end portion than the cover. The developing unit supports the protrusion when the cartridge is mounted thereon, and the casing pivots with the cover relative to the developing unit between a first position where the shutter closes the second opening and a second position where a third opening of the shutter overlaps the second opening.

A toner container includes containing chambers, a shaft member, rotary members, and stirring members. The containing chambers are arrayed in a first direction and partitioned from each other. The containing chambers contain respective toners of different colors. The shaft member extends in the first direction, passes through the containing chambers, and is rotatable about a rotational axis extending in the first direction. The rotary members are disposed in the respective containing chambers and each have a through-hole extending in the first direction. The rotary members are rotatable in response to rotation of the shaft member in an inserted state of the shaft member in the through-holes. The stirring members are supported by the respective rotary members and each extend in a second direction intersecting the first direction. The stirring members are pivotable in response to rotation of the respective rotary members. The stirring members have different pivoting positions upon pivoting.

A toner conveyance device includes a conveying screw having a shaft and a spiral blade. The spiral blade includes a start end-side blade adjacent to a bearing positioned at a start end part side in a toner conveyance path, a terminal-side blade adjacent to a bearing positioned at a terminal part side, and an intermediate blade. A toner discharge port is provided between the intermediate blade and the terminal-side blade. A spiral winding direction of the terminal-side blade is opposite to that of the intermediate blade, a spiral winding direction of the start end-side blade is equal to that of the intermediate blade, and a blade diameter of the start end-side blade and a blade diameter of the terminal-side blade are smaller than that of the intermediate blade.

A developer accommodating unit for accommodating a developer for image formation includes a flexible container provided with an opening 35a for permitting discharge of the developer, a frame for accommodating the flexible container and for accommodating the developer to be discharged from the flexible container, and an urging member 21 for urging a developer accommodating bag toward the frame for accommodating the developer accommodating bag 16. By this, it is possible to satisfactorily effect discharge of the developer from the flexible developer accommodating bag 16.

A developing apparatus includes a partition member disposed in a first chamber above a discharge space communicated to the discharge port positioned downstream of a return conveyance portion in the first direction, and configured to divide a space within a first chamber in a gravity direction. The partition member is configured to extend from a wall portion on a downstream side of a developer container to a position corresponding to a downstream end of a return conveyance portion or to a position further upstream beyond the position corresponding to the downstream end of the return conveyance portion in the first direction. A surface, opposed to a first conveyance screw, of the partition member is positioned downward in the gravity direction than an upper end of a first communication port and upward in the gravity direction than the first conveyance screw.

A cartridge includes a shutter that opens and closes when the cartridge is attached and detached to a developing unit or image forming apparatus. The cartridge includes a casing having a chamber with a first opening at one end portion allowing toner to flow out of the casing. The cartridge includes a cover that covers the first opening, movable with the casing and having a second opening allowing toner to flow out of the cover. The shutter is located at the one end portion and has a protrusion further from the one end portion than the cover. The developing unit supports the protrusion when the cartridge is mounted thereon, and the casing pivots with the cover relative to the developing unit between a first position where the shutter closes the second opening and a second position where a third opening of the shutter overlaps the second opening.

An image forming apparatus includes a rear-side frame member that is disposed on the rear side of an image forming apparatus body so as to extend in a vertical or substantially vertical direction; and a drive unit that includes a drive part. The drive unit is detachably disposed on an inner surface of the rear-side frame member such that the drive part faces outward from the image forming apparatus body.

A toner conveyance device includes a conveying screw having a shaft and a spiral blade. The spiral blade includes a start end-side blade adjacent to a bearing positioned at a start end part side in a toner conveyance path, a terminal-side blade adjacent to a bearing positioned at a terminal part side, and an intermediate blade. A toner discharge port is provided between the intermediate blade and the terminal-side blade. A spiral winding direction of the terminal-side blade is opposite to that of the intermediate blade, a spiral winding direction of the start end-side blade is equal to that of the intermediate blade, and a blade diameter of the start end-side blade and a blade diameter of the terminal-side blade are smaller than that of the intermediate blade.