Abstract: A straightening machine includes an array of flexible straightening rollers and an array of complementary rollers which alternate with the straightening rollers in direction normal to the axes of such rollers, the complementary rollers being arranged at a major surface of a deformable sheet-shaped material that faces oppositely to another major surface at which the straightening rollers are situated. A plurality of support rollers supports the respective straightening rollers, the support rollers being distributed along the length of the straightening roller and being individually adjustable as to their position with respect to a support roller alignment plane. During the straightening operation, a predetermined number of the support rollers is selectively positionally adjusted, and the remaining rollers are automatically positionally adjusted until abutment of all support rollers at the straightening roller is achieved, by simulataneously calculating the expression V/=/A/.multidot.