PURPOSE: To provide the titled system where nozzles jetting compressed air at both sides of the yarn-inserting slit of ending hole are set up in a specific state, thus enabling yarns of wide range of number counts to be brought to ending with sufficient strength.

CONSTITUTION: Compressed air jet nozzles 24, 25 are set up non-tangentially on the inner peripheral wall surface 26 of both sides of the slit 22 of a cylindrical ending hole 2. Said nozzles 24, 25 are so arranged that their sectional forms at right angle to the direction of air flow are of flat and long channel such as rectangle or ellipsoid at any position along their air flow routes. A compressed air jetting from the wall surfaces of both sides of the slit impinges on the both yarn ends superposed over a wide range of the superposed area to effect firm entanglement of the fibers at the both yarn ends, thus making the single fibers coexist mutually.