To optimize the ratio of the deep height dimension to the upper depth dimension of the weft guide groove, the cross section of the flow channel, individual inclination angles of the upper inner walls and the lower inner walls to increase the flow speed of the injected air flow from the weft inserting nozzle into the weft-guide groove without damage to the weaving.

In the reed for a air-jet loom having a weft-guiding groove (7) that is opened on the fabric side, the ratio of L1/H is 2-2.5, when the upper depth dimension is represented by L1 and the depth height dimension is represented by H. Further, the cross section area S of the flow channel defined with the straight line connecting between the upper corner (13) on the fabric side and the lower corner (14) of the weft guide groove (7) and the weft guide groove (7) is represented by the following formula: 30 mm2≤S≤45 mm2.