is blown into the bent pipe sp1 past the front of the weft feeler wf1 but does not reach the weft feeler wf2 because the weft length is measured exactly by the weft length measuring device d when the weft w reaches the weft feeler wf1 an output signal sf is generated from the weft feeler wf1 whereby a completion signal s10 is developed as an output signal of the and gate 13 with the completion signal s10 the flip flop 12 is reset and the operation signal s2 is extinguished so that the nozzle controller nc closes the on off valves vm and vsi to stop the operation of the main nozzle mn and that of the sub nozzle sni at this time the stretch nozzle sp continues to operate so there is no fear of the weft w becoming loose on the other hand with the completion signal s10 the flip flop 21 in the shed closing control section 20 is set as a result the relay ry operates and the main motor m is rotated at a low speed which is set by the speed setter ss whereby the warp shed can be closed through the loom shaft not shown and further through a shedding motion interlocked with the loom shaft this closed state of the warp.