PURPOSE: To stabilize bending precision by arranging a pipe bending mechanism and a pipe clamp and providing a clamp sliding mechanism moving a desired quantity to the side of the bending mechanism simultaneously with the bending.

CONSTITUTION: A clamp 3 on the bending side and a bending form 4 are provided at the middle position of a copper pipe 1 and the pipe clamp 5 is arranged between a reference stopper 2 and the bending clamp 3. Further, the clamp slide mechanism 6 is arranged to the clamp 5. The supplied copper pipe 1 is brought into contact with the reference stopper 2, cut off to prescribed dimensions, clamped by the clamp 5 and bent by the clamp 3 and the bending form 4. In this case, the clamp slide mechanism 6 operates by a quantity of bending slide optimum to the bending quantity to slide the clamp 5 to the bending side. Since dispersion in bending is dissolved, bending accuracy is stabilized.