PURPOSE: To improve the success rate of ending by installing a pick-finding auxiliary device on a suction mouth.

CONSTITUTION: An automatic winder consists of a traversing drum 13 which winds a string unwound from a feed bobbin around a winding package 14, an ending device disposed on a string traveling way, a rotatable suction mouth 16 which guides a string edge on the winding package side to the ending device, and a rotatable junction pipe which guides the string edge on the feed bobbin side to the ending device. A compressed air pipe 22 is fixed on top end upper surface of the suction mouth 16, and blow-out air flow 23 is blown off from a nozzle 22a of the compressed air pipe 22 to the surface layer 14a of the winding package 14. Blow-out air flow 23 loosens the string edge which is twined around the surface layer 14a, and the string edge loosened is sucked with air flow moving toward a suction port 16a.