A catheter system includes a shaft main body including an elongated hollow outer tube and an inner tube accommodated in the inside of the elongated hollow outer tube. The hollow inside of the inner tube is suctioned from the proximal end side thereof. The outer tube has an opening formed in a circumferential surface thereof and an attaching portion provided therein on the distal end side with respect to the opening. The inner tube can move in an axial direction with respect to the outer tube, and at least a distal end side end portion thereof can move back and forth between a proximal end side position with respect to the opening and the attaching portion. The inner tube has a cutting unit provided in the hollow inside of the distal end side end portion thereof and is capable of attaching to the attaching portion
