PURPOSE: To prevent any end breakage from occurring in checking a variation in yarn tension by controlling the position of a balloon regulating member so as to make a balloon in time of reeling become a proper size at the time of reeling yarn of a yarn feed bobbin.

CONSTITUTION: A winding unit 11 is equipped with a grooved drum 14, coming into contact with a yarn layer 13 of a roll package 12 and rotating this yarn layer, and a yarn guide 17 as a balloon regulating member installed in the upper part of a yarn feed package 16 erected on a tray 15, respectively. This yarn guide 17 is composed of installing a support member 19 to situate a tubular member 18 guiding yarn (y) to the drum 14 concentrically with the yarn feed package 16. The support member 19 goes up and down by means of an air cylinder 24 in a direction of moving the yarn guide 17 downward at a control point where yarn tension T suddenly goes up, and this control point is judged according to a winding diameter of the yarn feed bobbin 16 to be detected by a detecting means consisting of a phototube 28 and a reflector 29.