A sheet pressing device includes plurality of pressing members and a support member. The plurality of pressing members is provided on a downstream side in a discharging direction of fixing unit which carries out a fixing treatment over a sheet having an unfixed image transferred thereonto along the discharging direction. The plurality of pressing members presses both ends of the sheet in a direction along a surface of the sheet carried out the fixing treatment by the fixing unit and in a direction crossing the discharging direction. The support member supports the plurality of pressing members movably in such a direction as to approach or separate from the sheet when the sheet passes through the sheet pressing device.