To provide a method for a loom, for supplying wefts and preventing influence on fabric appearance caused by a deference between the twist number of an unreeled weft before switching and that after switching, even when supplying the weft by switching weft packages, and to provide a device for the method.

The method is characterized by comprising a step, wherein each weft 3 from a plurality of weft packages 5 respectively set on a plurality of pegs 10 is unreeled and is collected in a storage drum 12, and a step, wherein the collected weft 3 is supplied through a beating means 9 based on a supply timing, and when the weft is supplied from a package which is different from that from which the weft was supplied at the last timing, the weft package 5 supplying the weft 3 this time is selected so that the roll diameter difference between the remained roll diameter of the weft package 5 selected at the last timing and that of the weft package 5 selected this time is smaller than a predetermined diameter difference.