To improve the precision of a torsion flat steel and to remarkably shorten the working time by respectively fixing both ends of a flat steel, twisting the flat steel by rotating one side end while drawing one more side end, and producing the torsion flat steel.

In a rotary part 1 of a machine, a fixing part 3a to tighten and fix a flat steel 14 is provided at the end of a rotary shaft 2, a sprocket 4 is attached to the other side end, to be engaged with a chain and rotated with a motor 5. On the other band, a moving part 6 in which roller 7 is attached to its fixing part 3b to tighten and fix the flat steel 14 moves right and left along the upper frame of the body 8. Then, a wire 9 is attached on the rear of the moving part and a weight 11 is hung through a pulley 10. A stand 12 attached to a hydraulic cylinder 13 is provided under the weight, and the stand is moved up and down with the hydraulic cylinder 13. When the rotary shaft is rotated with the motor and the flat steel 14 is twisted, because it is made gradually shorter, the moving part is moved to the rotary part in the state of hanging the weight 11.