A straightener for straightening a metal strip and/or flat metal parts, having a number of lower straightening rolls which are mounted in a lower roll frame and a number of upper straightening rolls which are mounted in an upper roll frame. Stay bolts connect the upper and lower roll frame at a preselectable spacing, the stay bolts being assigned adjusting apparatuses for changing an effective length of the stay bolts, which effective length defines the preselectable spacing, and for compensating for changes in the effective length during operation. The adjusting apparatuses include a mechanically movable sliding wedge which changes the effective length of the stay bolts.