To prevent an adverse effect on machining accuracy by preventing a force other than the rotating force of a driving transmission side from being transmitted to the support section of a machining roller.

Plural pairs of bearing units 29 and 30 are disposed oppositely to one another in support frames 14A and 14B. A machining roller is fixed between the rotary shafts 32 and 35 of each pair of bearing units 29 and 30 via tapered connection parts 32a, 25a, 36 and 37 so as to be detached, and a wire is wound by a specified pitch between machining rollers. A motor 39 is actuated and connected to one machining roller 17 via pulleys 40 and 43 and a belt 44. Between the driven pulley 40 rotated by the motor 39 and the driving side rotary shaft 32 of one machining roller 17, an elastic coupling 45 is provided for absorbing the displacement of a direction orthogonal to an axis, which is applied to the driven pulley 43 by the tension of the belt 44.