An offset correction controller in a continuous tack welding machine of the present invention constrains a cylindrical steel plate using a plurality of cage rolls, butts edges in the width direction of the steel plate, and continuously performs tack welding. The offset correction controller includes a detection unit that detects an offset amount between the edges in the width direction of a butted portion of the steel plate, and an offset correction control unit that adjusts constraining forces of the cage rolls arranged on both sides of the butted portion such that the offset amount becomes smaller than a certain value when the offset amount detected by the detection unit is equal to or larger than the certain value, and reduces the constraining forces of other cage rolls when the offset amount does not become smaller than the certain value after the adjustment of the constraining forces of the cage rolls arranged on both sides of the butted portion.
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