Abstract: A tack-in system of an air jet loom, for forming a tack selvage at an edge section of a fabric. The tack-in system is comprised of a body of a tack-in device, which body is formed with a slit. The slit is located near an edge of an array of warp yarns. A weft yarn picked from a weft picking nozzle extends through the slit. The end section of the weft yarn picked and cut by a cutter is securely held in such a manner that at least a part thereof is located within the slit. A fluid jet nozzle is provided to eject a fluid jet from its opening which is located such that the fluid jet therefrom blows the weft yarn end section. The fluid jet from the fluid jet nozzle is so directed that the axis thereof crosses the cloth fell at an acute angle, thus securely pressing the weft yarn end section onto the cloth fell.