To provide a yarn winder capable of reducing damage to yarn by eliminating large winding of the yarn between an empty bobbin and a full bobbin during passing the yarn.

The yarn winder includes a bobbin switching operation of switching two bobbin holders 11, 12 from a winding position P1 to a waiting position P2 and vice versa, by which the continuously supplied yarn is wound around the bobbin at the winding position. A first regulating means 20 which regulates the yarn from the full bobbin side to the empty bobbin side is provided for a yarn Y between the empty bobbin EB and the full bobbin FB in passing yarn, and a second yarn regulating means 50 which regulates the yarn from the other side of the first yarn regulating means on the yarn layers of the full bobbin is provided, which is structured to prevent the yarn from being regulated in the diametrical direction of the full bobbin.