PURPOSE: To simplify roll adjusting work required when rolls are exchanged, by giving a specific structure to the connecting part of the driven shaft and driving shaft of the roll for a roll former provided with the upper and lower rolls.

CONSTITUTION: A connecting part 6 of a driven shaft 5 which transmits a rotating power to the upper and lower rolls of a roll former and a driving shaft which rotates the driven shaft 5 with a motor, is composed of a driving side claw plate 13 provided with a claw 13b of a projected or recessed shape at the end face which is inserted into the driving shaft 7 in such a way that the end face can only make sliding movements, a driven side claw plate 14 fixed to the driven shaft 5 and provided with a claw 14b of a projected or recessed shape at the end face, a core adjusting plate 15 which is provided with a projected or recessed claw 15a which is fitted to the claw 13b at one end and another projected or recessed claw 15b which is fitted to the claw 14b at the other end, and a member 16 which holds the core adjusting plate 15 on the claw plate 13. When the claw plate 13 is moved along the driving shaft 7 or the driven shaft 5 is approached to or separated from the driving shaft 7 together with a roll stand, the driving shaft 7 and the driven shaft 5 are easily connected to each other or separated from each other, and then, the roll exchange and adjustment of rolls can be made in a short time.