ROLLER LEVELER AND SHEET-MATERIAL FLATTENING

This roller leveler (100) for correcting a sheet material (S) is equipped with: a leveling roll unit (20) having a plurality of leveling rolls (6, 8) that rotate so as to thread the sheet material through while also taking in and pressing on the sheet material (S); pressure cylinders (4a, 4b) for pressing on the sheet material (S) via the leveling rolls (6, 8) at an entry-side and exit-side of the leveling roll unit (20); and a driving mechanism (15) for rotating the leveling rolls (6, 8) to thread the sheet material (S) through. The diameter (D) of the plurality of leveling rolls (6, 8) is given a value satisfying 0.5 < D/P < 0.9 in relation to a between-roll pitch (P) of the leveling rolls (6, 8), determined by the maximum required yield stress and maximum required sheet thickness for a sheet material that must be corrected.