A biliary tract drainage tube used to drain a biliary tract is provided with long external drainage tube 2 and internal drainage tube 3 that is provided on the tip of the external drainage tube so as to be separable from the external drainage tube. Both external drainage tube 2 and internal drainage tube 3 are placed in biliary tract Cd. Since internal drainage tube 3 can be left behind in the biliary tract by removing external drainage tube 2, another endoscopic procedure is not required when switching from external drainage tube 2 to internal drainage tube 3, and the burden placed on the patient can be lessened.
