PURPOSE: To make exchanging of roll units easy and improve workability by making the gears for roll driving installed parallel with aligned roll units freely movable forward and backward.

CONSTITUTION: In a roll forming apparatus in which continuously forming roll groups R, roll groups R are unitized at every several steps and roll units RU5 are exchangeable according to need, the gear groups RG8WRG10 for roll driving installed parallel with the roll units RU5 are placed on a freely forward and backward movable moving bed 2. This moving bed 2 is moved in the arrow direction on a base plate by the rotational feeding of screw bolts 11; at the same time, the gear groups RG8WRG10 are moved. Because of this, the central positions of the roll groups may be set always in the fixed positions on the base plate irrespective of the roll width of the exchanging units, thus the exchanging of the roll units becomes easy.