PURPOSE: To place a wire in a uniformly consumed condition in the peripheral direction generating no change of the wire in its rotary angle per unit length even when the wire changes it running speed by controlling the wire generating a rotary angular speed signal as the function of a feed speed of the wire.

CONSTITUTION: Feeding a wire 2 from a storage reel 1, the wire 2 is wound to a winding reel 5 via a feed roller 3 and a winding roller 4 while held to paired rotary rollers 9, 10 driven by motors 11, 12, and the wire 2, running while rotating, cuts a workpiece 8. Here a function generator 23 generates a rotary angular speed signal SIG-B with a feed speed signal SIG-C as the function of a signal SIG-A instructing a running speed of the wire 2, controlling a speed of motors 6, 7 and 11, 12 respectively through drivers 21, 22. Thus even when the wire changes its running speed, no change is generated in a rotary angle of the wire per its unit length, and enabling the wire to be placed in a uniform consumption state over the peripheral direction, the improvement of machining accuracy can be promoted.