PURPOSE: To obtain a coil former having an arbitrary ratio of length and breadth by a method wherein a slider mechanism to move in the axial direction and spool extension and contraction mechanisms of two pairs of top and bottom, right and left are provided around a rotary shaft, and the respective spool extension and contraction mechanisms are driven separately from the slider mechanism.

CONSTITUTION: The coil former main body of a coil former device 7 is constructed of a disk type flange 8 and a sleeve shaft 25 provided at the edge part of a rotary shaft 2. When a nut 17 is rotated, a ring slider 19 slides the shaft 25 right and left, slide bases 14a, 14b are transferred through studs 22, and parallel links 16, 16 stand up to extend expand blades 15a, 15a. Then when a shaft 32 is rotated, a feed screw 30 is transferred in the axial direction to slide slide- bases 14b, 14b, and expand blades 15b, 15b are extended. Moreover covering plates 36 are provided between the mutual plates 15a, 15b, and a rectangularly sectional coil former having an arbitrary ratio of length and breadth can be formed by controlling mutual fitting relation.