There is provided a method for transporting a fluid, in which even if the fluid is transported for a long period of time, dehydration after transportation is not needed, and the transported fluid can be used immediately after transportation. Specifically, there is provided a method for transporting a fluid, comprising steps of: dehydrating some of the transportation fluid during transportation by using a dehydration system comprising a separation membrane through which water permeates, and returning the dehydrated fluid to the transportation fluid so as to keep water content in the transportation fluid in a fixed range. In one embodiment, the transportation fluid is a liquid, and the dehydration system comprises a heater for heating the liquid to a temperature in a range in which the liquid does not boil, and a membrane separation apparatus for dehydrating the heated liquid, wherein the membrane separation apparatus is a PV method apparatus comprising a primary side chamber extending in an up and down direction to introduce the liquid from a lower portion thereof and discharge it from an upper portion thereof, a separation membrane in contact with the primary side chamber to allow water in the liquid to permeate through as a gas, and a secondary side chamber being located on the opposite side to the primary side chamber with the separation membrane held therebetween and being under a pressure lower than that in the primary side chamber.