CONCENTRATION METHOD AND CONCENTRATION SYSTEM FOR RAW MATERIAL LIQUID

Provided are a raw material liquid concentration method and a raw material liquid concentration system that can achieve a high flux even when using a raw material liquid that is rich in an organic solvent. An aspect of the present invention provides a method for concentrating a raw material liquid, said method comprising a concentration step for bringing a raw material liquid and an induction solution in contact via a forward osmosis membrane. The raw material liquid contains not less than 50 mass% of an organic solvent and a valuable substance. The forward osmosis membrane has a base material layer and an active layer. Either the induction solution contains a hydrophobic induction solute and the active layer is hydrophilic, or the induction solution contains a hydrophilic induction solute and the active layer is hydrophobic.