To provide a device for inspecting running state of weft to reduce the load on an operator.

The weft running state inspection device S1 is composed of a body 16 and an insertion member 17 having a thin form to enable the insertion into and extraction from a warp opening by pushing apart through the warps T. The body 16 is fixed to a sleigh 9 by an L-shaped attaching bracket 18 fixed to a side face, a bolt 19 and a nut 20. The insertion member 17 has a hollow space 23 formed inside the member and an opening 24 formed at the tip end of an intrusion part 21, connected to the hollow space 23 and directing to a weft path. A light projector 25 composed of a light-emitting diode is inserted and fixed in the opening 24. Accordingly, the intrusion part 21 of the insertion member 17 of the weft running state inspection device S1 is introduced into the warp opening by the backward rotation of the sleigh 9. When the rotation angle of the loom reaches a preset level, light is projected from the light projector 25 to the weft path to illuminate the weft. Since the light projector 25 emits light synchronous with the rotation of the loom, the running state of the weft Y can be observed and inspected in stopped state.