To control a weft having reached an opposite weft inserting side in an extended state in a proper state of warp.

In this auxiliary opening apparatus 2 equipped with a head 15 which is inserted from the vicinity of the outer edge of a warp at the opposite weft inserting side into an opening 6 of the warp 3 and extended in a fixed weaving width and with a driving means 16 which reciprocates and drives the head 15 at a fixed timing corresponding to the weft inserting and inserts the head 15 into the opening 6 of the warp 3, before the warp 3 is opened, the head 15 is inserted from the vicinity of the outer edge of the warp 3 in the opening 6 of the warp 3 into a fixed position in the weaving width direction then the warp 3 is brought into contact with the head 15 with the opening movement of the warp 3 so that a fixed opening state is maintained and head 15 is escaped from the opening 6 while force in the direction of weft inserting acts on a weft 8 in the opening 6 maintained by the head 15.