Abstract: A device for decurling flat printing materials for a machine for processing the printing materials has a guide surface section whereover the printing materials are drawable. The guide surface section are formed with a decurling notch, and with suction openings arranged along and in the decurling notch and penetrating the guide surface section, and an evacuation system fluidically connected to the suction openings. The suction openings are formed in successive groups thereof, and the evacuation system including a plurality of chambers, of which respective chambers are assigned to a respective one of the groups of suction openings, the chambers being selectively settable with at least one of equal and unequal negative pressures therein during operation, and a machine for processing the printing materials having the decurling device therein.