An apparatus for conveying sheets through a printing machine allows continuous monitoring of the position of a sheet with regard to a guide element over a long time period. There is provided a circulating conveyor element with grippers in which the sheet is held at a leading edge. A device for setting the position of the sheet can adjust the position with regard to a desired position. A measuring configuration measures the position and the presence of the sheet. A control device is connected to the device for setting the position and to the measuring configuration. The measuring configuration is mounted so as to circulate with the conveyor element.