A treatment tool is made to protrude at an appropriate position with respect to an endoscope while maintaining a high flexibility. Provided is a medical tube (1) including: a first lumen (4) that forms an endoscope channel by penetrating through a tube main body (2), which is constituted of a material possessing flexibility, in a longitudinal-axis direction； a plurality of second lumens (5 and 5a) that are capable of forming treatment-tool channels by penetrating through the tube main body (2) in the longitudinal-axis direction at a periphery of the first lumen (4) with spacings therebetween in a circumferential direction； a first indicator (12) that is provided on an inner surface in the vicinity of a distal end of the first lumen (4) and that specifies a circumferential-direction position of any one of the second lumens (5 and 5a) with respect to the first lumen (4)； and a second indicator (13) that is provided at a proximal end of the tube main body (2) and that indicates the second lumen (5a) specified by the first indicator (12).
