[Problem] To provide a catheter of a simple structure with which an embolization of a blood vessel can be removed and ultrasound images of the blood vessel can be acquired. [Solution] A catheter (10) is equipped with: a shaft (11) having an opening (20) at a part of a distal end-side side wall; a cutter (12) that is located in the vicinity of the opening (20) in an internal space of the shaft (11) and is movable in the axial direction (101) of the shaft (11); a balloon (23) that is disposed on the side opposite the opening (20) with respect to the axis of the shaft (11), and swells outward from the side wall of the shaft (11); and a phased array-type ultrasonic probe (17) that is disposed along the peripheral direction (102) of the outer peripheral surface of the side wall in the vicinity of the opening (20), at least on the same side as the opening (20) with respect to the axis of the shaft (11).
