A catheter assembly 100 has a catheter 60, a catheter hub 110, a guide wire 10, and a guide wire hub 120. The guide wire 10 has a guide wire rigidity changing portion 35 that gradually decreases in rigidity from a proximal side toward a distal side, and the catheter 60 has a catheter rigidity changing portion 85 that gradually decreases in rigidity from a proximal side toward a distal side. In the catheter assembly 100, the catheter hub 110 and the guide wire hub 120 are connected to each other in a state where the distal side of the guide wire 10 is exposed from a distal end of a lumen 71 of a shaft portion 70 and a guide wire rigidity changing point 37 and a catheter rigidity changing point 87 are aligned with each other in an axial direction.
