PURPOSE: To enable a material having a large spring back to be bent into a circular-arc shape.

CONSTITUTION: In a double roll forming machine 10, a roll 24 to be pressed is formed to an extremely small diameter, a supporting pressing member 26 of a rigid body bigger than the roll 24 and arranged in parallel with the roll 24 is provided with an inserting part 261 in the longitudinal direction, and the roll 24 to be pressed is inserted into it to be supported freely rotatably at several points in the longitudinal direction. Also, the rotary shaft 264 at one end of the supporting pressing member is supported freely rotatably and stoppably by a supporting mechanism 28; in addition, a pressing part 265 is provided on the side face in the longitudinal direction of the supporting pressing member; and the part 265 abuts on the inner circumferential surface of the material and presses the material to be worked at a desired position on the exit side where the material to be worked is released from the pressed state.