PURPOSE: To prevent a meandering by setting the tension on a strip according to the calculated tension so as to make the tension of the strand having the minimum tension of the strip the prescribed value with calculating the tension loss due to a roll.

CONSTITUTION: A processing unit 20 performs the tracking of a weld part based on the signal transmitted from the speed detector of each bridle roll and looper car position detector 24a and the running distance of the strip A from the weld point. It operates the proper total tension being capable to maintain the first strand tension as of the prescribed value and based on the result thereof it controls a motor 24. The strip tension in the first stand is thus maintained to the prescribed value and yet the meandering is prevented and the stabilized operation with the prescribed tension is enabled even in a high speed process line.