Abstract: A catheter equipped with an expansible member for expanding a constricted portion inside a blood vessel, comprises an inner tube having a first lumen whose tip is open; an outer tube disposing coaxially with the inner tube, having the tip thereof at a position recessed by a predetermined length from the tip of the inner tube and forming a second lumen between it and the outer surface of the inner tube; a contractible or foldable expansible member having the tip portion fitted to the inner tube and the proximal portion fitted to the outer tube, and communicating with the second lumen near the proximal portion; a first opening communicating with the first lumen disposed at the proximal portion of the inner tube; a second opening communicating with the second lumen disposed at the proximal portion of the outer tube; and a rigidity imparting member disposed in at least one of the inner and outer tubes so as to extend in an axial direction.