PURPOSE: To facilitate the treatment of a tail yarn, by placing a tail yarn clamping device composed of an upper slit ring, a cylinder and a guide member to a base of a spindle, thereby holding a tail yarn when the spindle is in stop stage and releasing the yarn when the spindle is in rotation.

CONSTITUTION: A base part of a spindle 2 is provided with a tail yarn clamping device composed of an upper slit ring 5, a cylinder 8 and a guide member 10. The guide member 10 and the upper slit ring 5 are fixed to the base of the spindle 2 and the cylinder 8 is placed between the guide member and the ring in a vertically slidable manner. The upper part of the cylinder 8 is made of a hard material to form a lower slit ring 6 and a yarn is clamped between the lower slit ring 6 and the upper slit ring 5. The lower part 7 of the cylinder 8 is made of an elastic material and has a structure radially expandable by centrifugal force. When the spindle 2 is rotated, the lower part 7 of the cylinder 8 is expanded by centrifugal force and the expanded part is engaged with the exterior slant guide face of the guide member 18 to lower the cylinder 8 and release the clamp of the yarn.