An introducer sheath is provided with a sheath tube which is formed of a tubular member provided with a hollow portion through which an elongated body is freely inserted and includes a distal portion having a tapering outer diameter and a main body portion having a constant outer diameter. The distal portion of the sheath tube includes a concave portion which is bent radially inward from an end portion, through which an elongated body protrudes, in a concave shape in a cross section parallel to an axial direction, and a convex portion which is contiguous to the concave portion and is bent radially outward in a convex shape in a cross section parallel to the axial direction.
