A sheet discharge device includes a discharge portion, a sheet stacking tray, a pair of alignment members and a pair of width regulation members, a shift portion, and a control portion. The pair of alignment members include an arm portion formed of a rigid body, and an alignment portion formed of a flat-shaped elastic material and fixed to a swingable end of the arm portion. In the sorting processing, when stacking a sheet at a first position, the control portion causes a first alignment member to ride on a top surface of the sheet and a first side edge of a second alignment member to make contact with the sheet, and, when stacking the sheet at a second position, causes the second alignment member to ride on the top surface of the sheet and the first side edge of the first alignment member to make contact with the sheet.

A sheet discharge device includes a discharge portion, a sheet stacking tray, a pair of alignment members and a pair of width regulation members, a shift portion, and a control portion. The pair of alignment members include an arm portion formed of a rigid body, and an alignment portion formed of a flat-shaped elastic material and fixed to a swingable end of the arm portion. In the sorting processing, when stacking a sheet at a first position, the control portion causes a first alignment member to ride on a top surface of the sheet and a first side edge of a second alignment member to make contact with the sheet, and, when stacking the sheet at a second position, causes the second alignment member to ride on the top surface of the sheet and the first side edge of the first alignment member to make contact with the sheet.