Abstract: Procedure for straightening a circular-saw blade (2), in which procedure the blade (2) is mounted on a shaft (3). The geometry of the blade is measured, the measured values are compared with reference values, deformations in the blade are straightened by means of blade treating elements (10, 11, 12, 13, 14, 15, 16, 23, 24), the blade is tensioned by means of working devices (13, 14), the blade (2) is rotated, lateral forces are applied to the blade (2), the effect of the forces on the blade (2) is measured while the blade is rotating, the measured values are compared with the reference values, and some or all of the operations mentioned above are repeated, if necessary, in a desired order, until the desired rigidity and straightness of the blade (2) have been achieved. The invention also relates to an apparatus for straightening a blade.