To attain high efficiency by solving the problem that conventional yarn winders generate such operation that the required amount of yarn cannot be removed or yarn is removed more than required because yarn defect information detected by a yarn clearer are classified into some preset information to be transmitted to a unit controller.

This winder having a piecing apparatus 14 controlled by the unit controller 21 and conducting piecing operation based on the detected signal of the yarn clearer 11 is provided with a clearer controller 20 determining, based on the detected signal, whether a yarn defect or not and, when it is determined to be a yarn defect, delivering data including the detected length of a defect part to the unit controller. The unit controller has an input part 21a inputted with data on the detected length and a control part 21c controlling piecing operation so that the defect length to be removed may meet the detected length of an inputted defect section of yarn.