To provide an air-jet loom consuming less compressed air and securing a sufficient quality of cloth.

This system for inserting a weft yarn into the air-jet loom (1) comprises a yarn reservoir (21), measuring devices (23.1, 23.2) capable of measuring the weft yarn (2) delivered from the yarn reservoir (21), in a plurality of air nozzles (3, 4, 5.1a-c to 5.na-c) for inserting the weft yarn (2) and a controlling system (10) connected to measuring devices (23.1, 23.2) so as to control the supply of compressed air to the air nozzles (3, 4, 5.1a-c to 5.na-c) in accordance with the measured values of the measuring devices (23.1, 23.1).