PURPOSE: To suppress the resistance of a flow path by making a flow path with a multi-circuit tube which is a single tube having two or more flow paths that are formed in parallel to each other in the lengthwise direction of the tube main unit.

CONSTITUTION: A multi-circuit tube 10 is formed by a tube main unit 12 of nylon and polyurethane of the like having flexibility. The first flow path 14 is provided with a half moon-shaped section penetrating in the lengthwise direction of the tube main unit 12. The second flow path 16 is provided with a section in half moon shape penetrating in the lengthwise direction of the tube main unit 12 further in parallel with the first flow path 14. A partitioning part 18 for dividing the first and second flow paths is internally formed with the tube main unit 12. As a result, manufacturing process is facilitated and, its efficiency can be improved. Since no rib is provided on the way of the flow path, its resistance can be suppressed.