PURPOSE: To obtain a fine quality winding package by detecting the tension of a yarn reeled out from a yarn supply package, varying the tensile force given to the yarn in comparison with the specified value and taking up the yarn on the winding package.

CONSTITUTION: In a yarn winder, a yarn Y is given a tensile force according to the position of a movable gate finger 10 of a tenser 6, that is, the turning angle of a movable plate 14 and taken up on a winding package. Said tensile force is detected by a yarn load sensor 6 having a pair of distortion gauges 34 and 35 adhered to the base part of a flexible pin 32, compared with the specified value 39 in a comparing circuit 38 via a detecting circuit 36 and an amplifier 37. If the tensile force exceeds the allowable range of the specified value 39 out of the allowable tolerance due to some reasons, the tensile force of the spring 19 is lowered via a driver 40 and a motor 22 to reduce the tensile force applied by the tenser 6. When the tensile force becomes below the limit of the allowable range, the tensile force is increased through the reverse action. Thus a fine quality winding package can be obtained.