To suppress backflow of a compressed air stream in a weft insertion nozzle of a weft insertion apparatus utilizing the compressed air stream. The compressed air stream is passed from a first annular chamber (15) through a straightening passage (16) and a compressed air stream passage (28) and jetted from a first jetting passage (29) into a joining passage (25). The compressed air stream in the first annular chamber (15) is made to inflow even from inlets (31) of second jetting passages (30) and jetted in a state of low pressure loss from the second jetting passages (30) in the weft insertion direction into a weft yarn passage (12). A weft yarn (5) is transported through the interior of the weft yarn passage (12) by driving force of the compressed air stream jetted from the second jetting passages (30). The compressed air stream jetted from the second jetting passages (30) drives the compressed air stream jetted from the first jetting passage (29) in the weft insertion direction in the joining passage (25) and acts as force for suppressing the backflow. Thereby, the driving force in the weft insertion direction can be increased. |