<p>Provided is a roll forming device, which is equipped with a forming roll capable of manufacturing such a mechanism simply and precisely as to input a rotating drive force to the forming roll. The roll forming device inputs the rotating drive force to the forming roll (2) from rotating force transmitting means (1). The forming roll (2) has roll-side engaging means (4) on the side where the rotating force transmitting means (1) extends toward the forming roll (2). The rotating force transmitting means (1) has input-side engaging means (3) on the side where it extends toward the forming roll (2). The roll-side engaging means (4) and the input-side engaging means (3) are engaged to input the rotating drive force from the rotating force transmitting means (1) to the forming roll (2).</p>
