Abstract: A straightening method particularly for an elongated metal member having a long longitudinally linear length, is carried out by an automatic straightening apparatus by the manner of preliminarily setting a plurality of points at which distortion are to be straightened. When it is required to straighten an amount of distortion to be straightened at a certain point, the amount is adjusted in consideration of the amounts of strains to be straightened at the other points by utilizing the method of least squares so that the elongated metal member has substantially a linearly straight shape. According to this manner, the amounts of the respective points of the long member to be straightened are adjusted. The distortion of the elongated metal member can thus be substantially straightened to a highly improved accuracy.