A dehydrating system using multiple water separation membranes aims to prevent damage to the water separation membrane units and also to take appropriate measures against decrease in water permeation rate of the water separation membranes. Provided is a dehydrating system (100) for removing water from a target fluid, including at least two water separation membrane units (1, 2, 3) connected in series in a flow direction of the target fluid; two or more heat exchangers (11, 21, 31) respectively provided in front of the water separation membrane units (1, 2, 3), each of the heat exchangers (11, 21, 31) raising a temperature of the target fluid to a temperature which is lower than a boiling point of the target fluid but close to the boiling point.