To detect a failure in clamping when a tip of a bundling wire cannot be clamped, and further to properly control the next starting position of the bundling wire.

When a clamp plate 28 of a bundling wire clamper 25 cannot clamp the tip of a loop of a wire W fed from a bundling wire feeding mechanism 1 to a nose 6, the wire W is drawn into the mechanism 1 during a process in which a feed motor 13 of the mechanism 1 is driven to reversely rotate to draw back the wire W. Therefore, no cutting operation of the wire W occurs even if the clamper 25 moves in parallel to a bundling wire guide hole 5 of a cutter block 4, resulting in no steep increase of the driving current of a twist motor 21 due to cutting load. The failure in clamping the bundling wire can be correctly detected depending on whether there is cutting load of the twist motor 21.