A tube for use in gastrointestinal tract which allows administration of nutritional, medicinal, or other agent into gastrointestinal tract while preventing detention of digestive juices in esophagus, and which also prevents reflux of gastric contents.A detention-proof lumen is provided in tube body 12 of gastrointestinal tract tube 10 furnished with tube body 12 equipped with main lumen 12b and expansion lumen, such as balloon lumen 12c, and with an expander such as balloon 15 expanded by delivery of liquid or gas via the lumen provided on outer circumferential surface of tube body 12. Said detention-proof lumen communicates from a part more toward the base than the part where expander is provided on outer circumferential surface of tube body 12 to a part more toward the tip than part where the expander is provided on outer circumferential surface of tube body 12. An inner tube 18 used for liquid supply is provided movably within tube body 12.
