Organic material liquid dehydration method

A method for dehydrating a feed solution comprising a first organic solvent, water, and a first solute, comprising

• a dehydration step of bringing the feed solution into contact with an organic draw solution comprising a second organic solvent via a forward osmosis membrane to obtain a dehydrated feed solution which is dehydrated to a water content of less than 1% by mass, wherein
• an initial water content of the feed solution in the dehydration step is 1% by mass or greater and less than 30% by mass, and an initial water content of the organic draw solution is less than the initial water content of the feed solution wherein the forward osmosis membrane is a composite membrane constituted of a separation active layer and a microporous support membrane, a solubility parameter difference ΔHSP between the organic draw solution and the separation active layer is ΔHSP<16 (MPa)0.5, and a saturation water content of the organic draw solution is 0.5% by mass or greater.