To provide a composition capable of minimizing a contact pressure to a wound bundle and also minimizing fluctuation of the contact pressure in a yarn winder.
The yarn winder has a contact roller 18 rotating by contacting an outer circumferential face of the wound bundle 3 formed by winding a yarn Y on a bobbin B, a roller support member 1 supporting the contact roller 18, and roller support member guiding means 17 and 17 movably guiding the roller support member 1 in the direction approaching the bobbin B and the direction separating from the bobbin B. It is provided with a winding thickening detecting means 15 detecting thickening of the wound bundle 3, a support member driving means 20 adjusting a position of the roller support member 1 in the direction approaching the bobbin B and the direction separating from the bobbin B, and a control means 30 controlling the support member driving means 20 so as to adjust the position of the roller support member 1 on the basis of a detection result of the winding thickening detecting means 15.