Provided is a guide wire for an ablation catheter with a balloon in order to prevent the tip of the guide wire from being mistakenly heated when ablation treatment is performed using the ablation catheter with the balloon and the guide wire. Specifically provided is a guide wire, wherein a deformed portion formed by bending and/or curving the guide wire is located in the region of 20-100 mm from the tip in the longitudinal direction of the guide wire, and in the deformed portion, the shortest distance between the central axis in the longitudinal direction of the guide wire and a point that is the farthest in the direction perpendicular to the central axis is longer than or equal to the minimum inside diameter of a lumen of a catheter shaft of an ablation catheter with a balloon used in combination with the guide wire, and shorter than or equal to 40 mm.
