Abstract: In converting a sliver into a roving on a bobbin-lead type roving frame, the speed of a bobbin is controlled in accordance with a slight difference between the roving tension and a predetermined tension, so that the roving can be wound onto the bobbin while a predetermined constant tension is maintained, in such a way that controlling of the speed of the bobbin can result from a fine adjustment of the delivery speed of a variable speed driving mechanism in accordance with the result of comparing a given frequency corresponding to the predetermined tension with a frequency of the vibration corresponding to a tension on the roving being wound, wherein such vibration of the roving is induced by lateral forces applied upon the roving running from the nip of the front roller to the top of the flyer at time intervals equal to time intervals corresponding to the frequency of the vibration of the roving, and such external forces are applied upon the roving during the time when the vibrating roving is moving or oscill