To provide an automatic winder capable of increasing a driving efficiency by suppressing the occurrence of troubles in carrying bobbin trays in the automatic winder having a bobbin carrying means for carrying bobbins put on the tray.

This automatic winder comprises the bobbin carrying means having a bobbin supply part for mounting the actual bobbins on the tray, a pick-finding part for picking up thread from the actual bobbins, a plurality of winding units for winding up the thread wound on the actual bobbins onto a package, and a bobbin extraction part for extracting the bobbins from which the thread is completely unwound up by the winding unit from the tray. The bobbin carrying means carries the bobbins by the tray circulating between these parts. The automatic winder also comprises a detection means detecting the bobbins passing specific positions in the automatic winder and when the detection means does not detect the passing of the bobbins for a prescribed time or detects the bobbins of a quantity exceeding a predetermined quantity, stops the carrying of the bobbins.