PURPOSE: To enable the stable feeding of weft yarn and measurement of the length with a high accuracy in a fluid injecting loom.

CONSTITUTION: This apparatus for measuring the length and delivering weft yarn in a fluid injecting loom is obtained by arranging a pair of disks, having rotation axial lines tilted at an equal angle in the upper and lower parts, synchronously rotating and sandwiching a passage line of the weft yarn, forming tapered mutually matching surfaces (8a) and (9a) in edge parts of mutually opposite surfaces of the disks 8 and 9, enabling at least either of the disks to move in the axial line direction thereof, sandwiching the weft yarn between the tapered surfaces, keeping the weft yarn in a linear contact state and enabling the transmission of the thrust.