PURPOSE: To eliminate roll changing work by mounting forming mills forming respective different sizes on a turning bed respectively, setting an optional mill on the pass line by only turning of the turning bed and directly connecting a driving shaft to a power side.

CONSTITUTION: Rolls are inched to discharge a remainder strip out of a fixed pass line 2 of a turning forming device after cutting a metal strip 1 remaining on the pass line 2. A welded coil 14 is evacuated out of the pass line 2, a driving shaft 20 is separated from a power shaft 26 by actuating a clutch mechanism 8, and the centerline or a new forming mill is set on the pass line 2 of the strip 1 by releasing a lock pin and turning a turning bed by a quarter rotation. Again, the above driving shaft is connected to the power shaft 26 with the mechanism 8. Hence, roll changing work accompanied with the above changing of outside diameter is completely eliminated and roll initial setting is also practically eliminated.