An image forming apparatus includes a cover portion and an auxiliary tray. The cover portion is displaced between a closing position for closing the supply port and an opening position for opening the supply port. The auxiliary tray is attached to a sheet stack surface of the cover portion, and supports the sheet, together with the cover portion at the opening position. The auxiliary tray is, either in a first attachment state or in a second attachment state, attached to the cover portion. In the first attachment state, a longitudinal direction of the auxiliary tray extends along a width direction that crosses a sheet insertion direction and the auxiliary tray is stored in the sheet stack surface. In the second attachment state, the longitudinal direction extends along the sheet insertion direction, and the auxiliary tray extends out from the cover portion toward an upstream in the sheet insertion direction.

An image forming apparatus includes an image forming unit that forms an image on a recording medium and an image forming apparatus body in which the image forming unit is provided, and on which a first manual feeding tray and a second manual feeding tray having a configuration different from the first manual feeding tray are selectively mountable at a same mounting position.

A post-processing device includes: multiple types of post-processing modules that are disposed at predetermined installation positions within the post-processing device and each execute post-processing to an output sheet on which an image is formed; and a controller that (i) detects the post-processing modules at the installation positions and (ii) determines and controls adjustment contents of the post-processing modules based on a detection result.

A sheet processing apparatus includes a pair of belts, a water supplying unit, a curving unit and a controller. The pair of belts defines a conveying path for holding and conveying a paper sheet. The water supplying unit supplies water to outer surfaces of the belts. The curving unit curves the conveying path defined by the belts. The controller makes the water supplying unit supply water to the outer surfaces of the belts, and makes the belts convey the sheet between the belts in a state where the conveying path is curved by the curving unit to correct the curling of the sheet.

An image forming apparatus includes one or plural forming devices that form respective images on a recording medium that is being transported, a fixing device provided on a downstream side with respect to at least one of the forming devices in a direction of transport of the recording medium and that fixes the images formed on the recording medium, a delivering device that receives the recording medium transported in a first direction and discharges the recording medium in a second direction that is different from the first direction, and a supplying device that supplies the recording medium to any of the forming devices or to the delivering device. The forming devices, the fixing device, the delivering device, and the supplying device have respective housings and are each joinable to any of the other devices.

A cover member attachment/detachment structure includes a first engagement part and a second engagement part. The first engagement part is formed in one of a portion to be protected or a cover member attached to the portion to be protected. The second engagement part is formed in the other of the portion to be protected or the cover member attached to the portion to be protected. The second engagement part is capable of engaging with the first engagement part. The first engagement part is made of magnetic material. The first engagement part is magnetically movable from an outside of the cover member without contact between a locking position where the first engagement part is engaged with the second engagement part and a lock releasing position where the first engagement part is disengaged with the second engagement part.

An optional device of the present disclosure is attachable and detachable with respect to an image forming apparatus via a connection member fitted to a side face of a main body of the optional device. The connection member includes a shaft, a connector, and a lock member. The shaft is supported by the main body to be slidable in an axial direction. The connector is fixed to the shaft and coupled to the image forming apparatus. The lock member is capable or restricting movement of the shaft in the axial direction. A position of the connector is adjusted by releasing the restriction placed on the shaft by the lock member and then sliding the shaft in the axial direction.

An image forming apparatus is provided. The image forming apparatus includes a main body; a first unit detachably attachable to the main body; a second unit which is arranged adjacent to the first unit and which is detachably attachable to the main body; and a cover which is located on the front side of the second unit relative to the detaching direction of the first and second units while supported by the second unit and which is openable and closable, wherein opening the cover permits detaching of the first unit from the main body and attaching of the first unit to the main body.

A sheet conveying device has a body and a frame supporting it, and is insertable or extractable along a sheet stacking face formed in an in-body discharge space in an image forming apparatus and having an inclined face with an upward gradient toward the downstream side in the sheet discharge direction. On the face of the frame opposite the sheet stacking face, a plurality of first and second wheels rotatable in the insertion or extraction direction are provided downward of the center of the opposite face in the insertion direction. The first wheels are arranged downstream of the second wheels in the insertion direction, and protrude from the opposite face farther than the second wheels. The first wheels fit into a concave portion formed in the sheet stacking face by the inclined face and thereby enable the second wheels to make contact with the sheet stacking face.

A relay conveyance device detachably mounted on an image forming apparatus body is provided with a fixing member that holds a mounting state of the relay conveyance device to the image forming apparatus body. The fixing member is provided with a relay connector that relays the image forming apparatus body and the post-processing device. The post-processing device is electrically connected to the image forming apparatus body via the relay connector.