Patent attributes
A catheter assembly includes an outer catheter and an inner catheter. The inner catheter has an accommodation unit which can be positioned on a farther distal side than an outer catheter body in a state where an inner catheter body is inserted into the outer catheter body, extends in a proximal direction from the inner catheter body, and can accommodate an outer catheter distal portion so as to surround an outer circumference thereof in a state where the outer catheter distal portion formed at a distal end of the outer catheter body is reduced in diameter. The outer catheter distal portion can be separated from the accommodation unit and can expand in diameter by moving the inner catheter body in a distal end direction relatively with respect to the outer catheter body from a state of being accommodated in the accommodation unit.