Abstract: There is provided a core pin for injection molding of a ferrule accompanied by a small amount of wear by forming a core pin constituted by a circular cylinder portion having a first diameter at a portion thereof for forming one end face of the ferrule and having a first angle of inclination by which a diameter thereof is enlarged toward other end thereof, a circular cone portion having a second diameter larger than the first diameter at a portion thereof for forming other end of the ferrule and having a second angle of inclination an angle of which is larger than the first angle of inclination by which a diameter thereof is reduced toward the one end face and a curved face in contact with the circular cylinder portion and the circular cone portion and having a section in a circular arc shape.