PURPOSE: To heighten the precision by correcting the diameter and pitch of the existing helical coil.

CONSTITUTION: Feeding rollers 22, 23 which are abutted with either of the inner or outer circumference of helical coil H at the central part of the device body 2 that the helical coil H is mounted are provided. A pressing member 8 providing a pair of bending rollers 12, 13 is provided freely movable to the upper and lower directions between the feeding rollers 22, 23. A engaging member 35 composing a pair of pitch rollers 41, 42 being arranged parallel is provided freely movable to the front and back direction of the device body 2 at the side directions of the feeding rollers 22, 23. The diameter is corrected by driving with rotating the feeding rollers 22, 23 after the feeding rollers 22, 23 are brought into contact closely with the helical coil H, elevating and lowering the pressing member 8, and deforming with bending the helical coil H with the bending rollers 12, 13 while sending the helical coil H to the circumferential direction. At the same time, the pitch of helical coil H is corrected by mutually moving the engaging member 35 to the opposite direction of the helical coil H.