PURPOSE: To secure the excellent operation performance and permit the yarn relaying having the sufficient joint strength by successively arranging the first clamp device, yarn cutting device, yarn elongation pulling lever, and the second clamp device, on both the sides, having a yarn relaying nozzle which can generate a turning air stream inside, interposed.

CONSTITUTION: When yarn relaying is carried out between the terminal end Ya of the yarn of a supplied yarn package in release and the starting end Yb of the yarn of a preparatory supplied yarn package, the yarn end Ya is clamped by the third clamp 15, and then inserted into a yarn relaying nozzle 17 from a slit 18 of a yarn relaying member 3 through the guide groove 43 of a fork guide 9 and a separating guide 30, and then clamped by the second clamp 12. Similarly, also the yarn end Yb is inserted and clamped. In this state, clamps 4 and 5 are closed through a link, lever, etc., by the operation of an air cylinder, and the yarn ends Ya and Yb are engaged and elongated by the swing of the yarn elongating pulling-in levers 10 and 11. Then, the high pressure air is jetted into a yarn relaying nozzle 17, and the envelope of an elongated filament is generated, and yarn relaying is carried out.