A catheter assembly comprises an outer catheter including an outer catheter body and an outer catheter hub at a proximal portion of the outer catheter body and an inner catheter including an inner catheter body insertable in the outer catheter body, a tip at the distal portion of the inner catheter body which is rich in flexibility, and an inner catheter hub at the proximal portion of the inner catheter body adapted to be coupled to the outer catheter hub. The inner catheter body includes a flexible section connected the tip, a physical property transition section on the proximal side of the flexible section, a first body section on the proximal side of the physical property transition section, a second body section on the proximal side of the first body section, greater than the first body section in flexural rigidity, and having a reinforcing material layer.
