To control the diffusion of a jet water flow.

The weft inserting nozzle comprises a straightening part arranged between a ring-shaped chamber to which pressure water is supplied and a pressure water nozzle and a needle inserted into the straightening part. The straightening part is equipped with a plurality of straightening walls which are extended in the radial directions and the axial direction of the straightening part and arranged at intervals in the circumferential direction and with a plurality of straightening flow channels composed of the adjoining straightening walls and inward faces positioned between them. The needle is inserted into the straightening part and forms a ring-shaped flow channel extending along the needle in cooperation with the straightening part. Each straightening flow channel is opened to the ring-shaped chamber and the ring-shaped flow channel and a plurality of the straightening flow channels form a plurality of kinds of straightening flow channels mutually different in elements related to a velocity.