To prevent the generation of an abnormal tension applied to a weft yarn at the completion of the travel of the weft yarn by installing a tension relaxing means for positively changing the weft yarn tension in a fluid injection type loom.

This weft yarn tension relaxing device in a fluid injection type loom performing a weft insertion by a fluid injecting means from a weft yarn wound body 2 through a feeder 3 and a nozzle 14, is obtained by installing the feeder 3 functioned by a solenoid and equipped with a hooking pin 4 for supplying a set length of the weft yarn, and a tension relaxing means positioned on the weft yarn passage and at the down stream of the feeder 3, rotating synchronously with the main shaft rotation of the loom and having a guide pin 8 at a suitable position from a center of rotation thereof.