A catheter assembly is disclosed, which includes a catheter, a catheter hub, a guide wire, and a guide wire hub. The guide wire has a guide wire rigidity changing portion that gradually decreases in rigidity from a proximal side toward a distal side, and the catheter has a catheter rigidity changing portion 85 that gradually decreases in rigidity from a proximal side toward a distal side. In the catheter assembly, the catheter hub and the guide wire hub are connected to each other in a state where the distal side of the guide wire is exposed from a distal end of a lumen of a shaft portion and a guide wire rigidity changing point and a catheter rigidity changing point are aligned with each other in an axial direction.
