the like are changed to the tail yarn treating apparatus of the present invention the wrapping number of the tail yarn around the tail yarn gripping means 11 is gradually adjusted to less than 1 turn so that the yarn underwindings not shown in the drawings which are the residual yarns of the previous separated tail yarn 12 39 remaining in the tail yarn gripping means 11 are automatically released prior to the production operation in this stage if the grooves 19 are radially outwardly formed on the upper surface of the lower slit ring 6 as shown in fig9 and 10 the yarn underwindings not released from the tail yarn gripping means 11 can be removed by sliding a hook like tool having a hook shaped tip not shown in the drawings along the grooves 19 radially formed moreover the tail yarn of the yarn y is engaged with upper edge portions 19 39 of the grooves 19 radially formed and therefore the effect of fixing the tail yarn to the tail yarn gripping means 11 is further improved further any number of grooves 19 radially formed may be used without limitation though 3 grooves are formed in this embodiment usually 2 to 6 grooves are suitable in fig9 and 10 the lower.