A tubular member 2 is formed of a resin material so as to have an inner passageway 2. A thin plate is shaped into a spiral along the perimeter of the tubular member 2 to form a reinforcement member 3. The reinforcement member 3 is buried in a peripheral wall 2a of the tubular member 2. The tubular member 2 and the reinforcement member 3 have curved shapes conformable to the shape of the pharynx 100. The tubular member 2 and the reinforcement member 3 are inserted from the oral cavity 102 into the pharynx 100 and retained there. A medical instrument is guided to the esophagus 103 through an inner passageway 2b of the tubular member 2.
