PURPOSE: To perform the straightening of the deviation from the roundness and bend of a steel pipe in a one stage at the same time by arranging a tandem in a three rolls shaft direction a working unit to apply the compression load to the four places of on the outer surface of a pipe and by sliding alternately the steel pipe holding position.

CONSTITUTION: A steel pipe 11 to be corrected is set to bridge among three stands 11, 12, 13 and to position in parallel to the rolls between parallel rolls 51, 52 of the upper side and parallel rolls 61, 62 of the lower side. A rod 14 of a hydraulic ram unit 13 is stretched to push up the rolls 61, 62 of the lower side and a compression load is roll-loaded on the steel pipe 11. Then, the roll-load is removed by setting the pipe rotation to ≥one rotation under pipe rotation. The steel pipe 11 bridging among three stands 11, 12, 13, which is being rotated, receives the necessary bending force due to the slip of a holding place A among stands and sufficient effect is obtd. in respect of bend straightening.