To provide a device for turning over sheets which operates with high precision, using a gripper which closes at the forward edge and the rear edge of a sheet simultaneously.

The device for turning over sheets by means of a transfer cylinder is of such a construction that a turning-over/storing drum 14 and an additional conveying element 7 are arranged opposite to each other on a transfer cylinder partitioned by two sheet guide cylinders 2 and 20 and a rotary printing machine for processing the sheets are operated in a single printing mode and a perfect printing mode. The transfer cylinder 9 can be driven in mutually opposite rotating directions 37 and 38 when set in the single printing mode and the perfect printing mode. Further, a plurality of gripper systems 12, 15, 25, 40, 44 and 46 which work in both opposite rotating directions 37 and 38 of the transfer cylinder 9, are mounted along the virtual outer peripheral face 10 of the transfer cylinder 9.