To provide a relay pipe of an automatic winder having such configuration that a holder and a disc are abutted always in a close adhesion condition to grip a yarn securely.

This relay pipe 1 has the configuration for catching a yarn Y on a yarn supply bobbin side by a suction pipe 1B and a yarn clamp 1A mounted in a tip part of the suction pipe. The yarn clamp 1A is provided with the holder 2 provided in the tip part of the suction pipe 1B and having a yarn insertion hole and the disc 3 abutted on the yarn insertion hole so as to oscillate. The disc 3 adheres closely to block the yarn insertion hole 6 of the holder 2 to grip the yarn Y.