A sub-nozzle in an air injection type weaving machine in which fluffing or the like caused by contact thereof with warp etc. does not occur, and for which its manufacture and control is facilitated. A sub-nozzle jetting a high-speed air flow for acceleration toward weft thrown from a main nozzle to between warps when they are raised and lowered to form shed opening comprises a holder connected to the side of a supply source of compressed air and a nozzle head connected to the holder, where at least the nozzle head is integrally formed by a high-strength glass material and occurrence of warp damage or wear of the nozzle head per se is restrained by the smoothness of its surface.