To easily manufacture a corrugated sheet having different corrugated height at a desired position, in a low cost by pressing the desired position of the corrugated sheet with one pair of pressing blocks after corrugating process.

One pair of the pressing blocks 2, 3 having flat pressing surface 2a, 3a each are prepared and the desired position of the corrugated sheet 1 is pressed with both pressing blocks 2, 3. By this method, since the top parts of each corrugated part in the corrugated sheet 1 is fallen down with the pressing surfaces 2a, 3a of the pressing blocks 2, 3 and crushed, the corrugated sheet 1 before pressing process is worked to the corrugated sheet having partially low corrugated height. In this work, a prescribed value of tension force is given in the longitudinal direction of the corrugated sheet 1 so as to cancell the elongating strain caused by crushing of the corrugated top part of the corrugated sheet 1 to prevent the warp and the waviness of the whole corrugated sheet. Then, such a tension force is set according to the material, thickness, width size of the corrugation, shape, crushing quantity, etc., of the corrugated sheet 1.