A guide sheath, which is configured to be guided by an internal introduction device and be inserted into a body and which has a channel through which a medical device is capable of being inserted so as to guide a distal end of the medical device to a target area, includes: an elongated member extending along a longitudinal axis； and a bent section which includes soft sections having predetermined bending stiffness, and hard sections having bending stiffness larger than the soft sections and provided in such a manner that the soft sections and the hard sections are alternately disposed in the longitudinal axis, and which is provided at a distal end of the elongated member and protrudes from a distal end of the internal introduction device so as to be bent by an external force.
