A swaging tool in which the pinhead of a fastening pin is positioned on one plate of a pair of plates through which the fastening pin is passed, the pintail of the fastening pin is positioned on the other plate, a collar mounted on the pintail side of the fastening pin is moved to the pinhead side so as to be brought into contact with the plate, the collar is swaged to the fastening pin in the state of contact with the plate, and a tensile load is applied to the pintail to break and remove the pintail, whereby the pair of plates are fastened; wherein the tool is provided with a swage die in which there is formed a swaging hole that is brought into contact with the collar to swage the collar, a low-friction coating film being formed on the inner peripheral surface of the swaging hole.