A sheet feeding device includes a sheet supporting unit, a sheet feeding unit, and a regulating member. The regulating member includes a supporting surface portion on which the sheet is placed, and a regulation surface portion provided continuously with the supporting surface portion and configured to regulate the position of the sheet in a width direction. The supporting surface portion includes a supporting surface color indicating portion including an end portion of the supporting surface portion on a side of the regulation surface portion and having a color with brightness of 7 or less in the Munsell color system. The regulation surface portion includes a regulation surface color indicating portion including an end portion of the regulation surface portion on a side of the supporting surface portion and having a color with brightness higher than the brightness of the supporting surface color indicating portion.

A sheet stacking device includes a sheet stacker, an image capturing device, and circuitry. The sheet stacker stacks a sheet. The image capturing device captures an image of a whole face of the sheet stacked in the sheet stacker. The circuitry detects a size of the sheet stacked in the sheet stacker, whether the sheet stacked in the sheet stacker is a last sheet, or whether an image is formed on an image forming face of the sheet, based on image data of the image captured by the image capturing device.

A supply device configured to supply a medium to a processing unit configured to perform processing on the medium, the supply device including an accommodating unit configured to accommodate a plurality of the media in a state of being stacked therein and a vibration imparting unit configured to contact ends of the plurality of media accommodated in the accommodating unit to impart vibration to the medium.

A sheet storage device includes a case, a lift plate, and a lift attachment. The lift attachment is fixed, in a detachable manner, to a central portion of the lift plate in a width direction. The lift attachment supports a lower surface of the sheets stacked on the lift plate at a position higher than the upper surface of the lift plate. The lift attachment includes a base portion and a pair of arm portions. The pair of arm portions are respectively formed to extend from an end portion of the base portion that is on a downstream side in the sheet feed direction, to opposite directions in the width direction.

A supply device configured to supply a medium to a processing unit configured to perform processing on the medium, the supply device including an accommodating unit configured to accommodate a plurality of the media in a state of being stacked therein and a vibration imparting unit configured to contact ends of the plurality of media accommodated in the accommodating unit to impart vibration to the medium.

A sheet storage device includes a case, a lift plate, and a lift attachment. The lift attachment is fixed, in a detachable manner, to a central portion of the lift plate in a width direction. The lift attachment supports a lower surface of the sheets stacked on the lift plate at a position higher than the upper surface of the lift plate. The lift attachment includes a base portion and a pair of arm portions. The pair of arm portions are respectively formed to extend from an end portion of the base portion that is on a downstream side in the sheet feed direction, to opposite directions in the width direction.