Sheet post-processing unit and image forming apparatus

A sheet post-processing unit which includes a sheet stacking portion, a sheet conveying portion, an intersectional moving device, a vertical moving device, an intersectional regulating member, and a controller. The sheet stacking portion stacks sequentially discharged sheets. The sheet conveying portion conveys each sheet stacked on the sheet stacking portion. The intersectional moving device moves the sheet conveying portion in a direction intersecting with a sheet discharging direction. The vertical moving device moves up and down the sheet conveying portion in a vertical direction. The intersectional regulating member aligns each sheet by contacting an edge of each sheet. The controller controls the intersectional moving device and the vertical moving device to move the sheeting conveying portion, and to press-contact the sheet conveying portion to an upper surface of a sheet and separate it from the sheet.