A guide wire port is formed in a midway position, in an axial line direction, of an outer shaft. A core wire extending across the guide wire port is provided in an outer tube hole of the outer shaft. The core wire has a leading end side area positioned further to a leading end side than the guide wire port and a tapered area provided on a base end side of the leading end side area. The tapered area has a first tapered area including a same position as the guide wire port in the axial line direction and a second tapered area provided continuously from a base end side of the first tapered area. A rate of increase of a transverse cross-sectional area from the leading end side toward the base end side is larger in the first tapered area than in the second tapered area.
