A distal end portion 2B of the core has a structure of a combined truncated cone 26 formed by connecting truncated cones satisfying a predetermined relational expression. An outer diameter ratio between the maximum outer diameter and the minimum outer diameter of the combined truncated cone 26 is greater than the outer diameter ratio between a large diameter proximal portion and a small diameter distal portion of an inner coil 4, and is greater than the outer diameter ratio between a large diameter proximal portion and a small diameter distal portion of the outer coil. Because of this, the rotation angle of the proximal side is reduced when rotation operation is performed and the torsional moment toward the distal end side is increased. Thus, the perforation performance at the completely occluded lesion can be improved.
