PURPOSE: To make storage of yarn smooth and prevent quality deterioration of yarn due to a ravel of yarn by inserting slack tubes into a suction duct and providing suction holes on both wall surfaces facing each other in said insertion part.

CONSTITUTION: Slack tubes 4 are inserted into a suction duct 3 and suction holes 9 are provided leaving a proper space on both wall surfaces 8, 9 facing each other in the aforementioned insertion part 6 of the slack tubes. Since the yarn introduced into the slack tubes 4 at the time of yarn breakage are drawn near toward the side of the suction holes of said wall surfaces by the negative pressure acting on the suction holes 9 on the tube wall surface, and the yarn in the slack tubes 4 are absorbed as well as pulled out in the state where they are separated each other, the yarn are sucked and energized in the direction where they separate each other even at the turn back part of the yarn in the slack tube 4, turn back describing large circular arcs, and a ravel of the yarn being sucked can be prevented.