To enable sure delivery of a defective yarn to a discharge apparatus.

A method for treating weft in a loom comprises stopping a reed sley at a position in which a stream from a guide nozzle is directed to the neighborhood of an intake port when changing the position of the weft to the neighborhood of the intake port, in the loom changing the position of the weft passing through a weft-inserting nozzle to the neighborhood of the intake port by jetting the stream from the guide nozzle arranged in the reed sley and unreeling the weft from the upstream side of a weft nozzle.