To save the labor for changing the weaving width of a rapier loom.

The weaving width of fabric is changed by stationarily keeping the position of the fabric edge of the weft insertion starting side. The position of weft delivery from the feeding rapier head 11 to the receiving rapier head 12, i.e., the meeting position of both rapier heads 11, 12 and the retreating positions of both rapier heads are unchanged. The position of a trimmed selvage forming apparatus 67 at the weft insertion end is varied according to the change of the position of a woven fabric edge of the weft insertion end. The position of an electromagnet 32 for releasing a weft from the receiving rapier head 12 is changed according to the change of the position of the woven fabric edge of the weft-insertion end.