To prevent the falling off of a weft piece entangled with a trimmed selvedge from a trimmed yarn even by reversely driving the loom.

A false-twisting spindle to twist a trimmed selvedge holding a weft piece on a trimmed yarn is rotated exclusively in one direction by a single direction rotating means. The twist of the false-twisted trimmed selvedge is not released and, accordingly, the weft piece entangled with the trimmed yarn of the trimmed selvedge is kept on the trimmed yarn owing to the prevention of releasing motion.