Abstract: A device for correcting a flexible material web that is guided to a processing machine, wherein the underside of the material web incorrectly points upward due to wrongly connected web ends or due to twisting. The device comprises a rotatable pair of cylinders that is arranged on a rotating device fixed on a frame and causes the material web to be turned by 180° about its longitudinal axis such that the underside of the material web once again correctly point downward. The device also comprises a stationary pairs of cylinders that are respectively arranged upstream and downstream of the rotatable pair of cylinders, particularly in the region of the respective face sides of the frame. The rotatable pair of cylinders can be displaced along the frame and the cylinders of the first and/or the second stationary pair of cylinders and of the rotatable pair of cylinders can be moved into an open position and a closed position.