A locking member (45) with which a binding material w is engaged, and a hook (46) constituting a twisting means are fixed to a swing member (43) provided on a spindle. A continuous wire type binding material w is fed in the direction crossing the axis of the spindle, and a front end portion of the binding material is engaged with the locking member (45), whereby a starting point at which the binding material starts being bent in the shape of the letter "U". The binding material w is then sent out to a surrounding guide (5) and guided into and area around materials to be bound a as the binding material is bent by a feed force into a substantially U-shaped binding material comprising two divisional wires, and the locking member (45) and hook (46) are turned unitarily to intertwine a front bent end portion of the binding material with a rear end portion thereof at the other side, whereby the articles are bound. Accordingly, articles can be bounded tightly in a single winding action by automatically bending a continuous wire type binding material into two divisional wires.