A sheet processing device for pressing a fold line formed in a sheet, the sheet processing device comprises a pressing portion configured to press a sheet while rotating about a rotation axis. The pressing portion includes a pressing unit having a projecting shape, disposed over a predetermined range in a direction of the rotation axis to have a position in a rotation direction about the rotation axis changed according to the direction of the rotation axis, and an impact absorbing member provided at a part of the pressing unit of the pressing portion, abutting on the sheet at first in the rotation direction of the pressing portion, the impact absorbing member configured to reduce impact upon abutting on the sheet.