PROBLEM TO BE SOLVED: To provide a crimp tool capable of securing a small outside diameter of a stent on the balloon part of a catheter and maintaining a state of reliably installing the stent on a balloon. SOLUTION: A stent crimp tool to reliably/uniformly crimp a stent 10 on a catheter 11, is composed of a base having two vertical support bodies spaced mutually and a coil-shaped tension spring having one end installed on a shaft and the other end installed on one vertical support body. When the stent 10 is loaded on the balloon 14 part of the catheter 11 and a stent/catheter assembly is also inserted into an axial directional space in the coil-shaped spring, a user can uniformly crimp the stent 10 on a balloon 14 by contracting the coil-shaped spring by twisting the coil-shaped spring by rotating the shaft.