To provide a weft tension device of a fluid jet loom equipped with an air jet nozzle and a through-hole member in which one of ends stands to face the nozzle, capable of strongly drawing the weft, even when air jet pressure from the air jet nozzle is more reduced than ever, by contriving to improve the through-hole member.

This weft tension device of the jet loom is equipped with the air jet nozzle 8 and the through-hole member 10 in which one of the ends stands to face the nozzle, wherein the through-hole member 10 has at least one or more communicating openings 13 for communicating with the outside on its side wall. The communicating openings are positioned on the upstream side from a point to which the tip of the caught weft reaches. Further, the communicating openings are positioned at a part of 1/4 of the total length of an air flow path of the through-hole member from the upstream side to 5/6 thereof. Holes are used as the communication openings.