To provide a tension device with which fluttering of a workpiece is dissolved and stable tension is applied, in a press line which is operated at high speed.

The tension device 10 is provided with a magnetic body 12, a releasing cylinder 14 and a magnetic force adjuster 15, and installed in a place where the workpiece W on the press line flutters greatly. In the magnet body 12, a permanent magnet the upper face of which is arranged to an S pole and a permanent magnet the upper face of which is arranged to an N pole are disposed on both right and left sides of the center line in the direction of conveyance. By arranging the releasing cylinder 14 and the magnetic force adjuster 15 under the magnetic body 12, the magnetic body 12 is moved in positions where magnetic force is applied to the workpiece and a position where the magnetic force is not applied to the workpiece and also the height of the magnetic body 12 is adjusted so that the magnetic force can be applied to the workpiece W at the proper position.