PURPOSE: To permit the taking-up operation at a high speed by reducing the height of a winder by judging the state of yarn by a slab catcher and carrying out the replacement of a yarn feeding bobbin or yarn relaying, in a winder for taking up yarn onto a package from the yarn feeding bobbin.

CONSTITUTION: A winding unit W is equipped with the first suction arm 9 which suction-holds the thread edge on a thread feeding bobbin 1 side which is suction-held by a yarn trap 8 and leads the thread edge to a yarn relaying device 7 the second suction arm 10 which suction-holds the thread edge on a package 3 side and leads said thread edge to the yarn relaying device 7, and the yarn relaying device 7 connects the both thread edges by the action of the turning air stream. Therefore, when a slab catch 6 detects the no- existence of thread, or detects the no-existence of thread after the advance of the thread edge, replacement of the thread feeding bobbin 1 is carried out, while if a thread cut signal is transmitted or the no-existence of thread after the retreat of the thread edge is detected, the thread joining of the thread edge on the thread feeding bobbin 1 side and the thread edge on the package 3 side is carried out.