PURPOSE: To advantageously obtain the subject concentrated solution in concentrating a highly diluted aqueous solution of ethanol using a pervaporation film of ethanol preference transmission type by collecting vapor at the transmission side of the pervaporation film using a condenser, and feeding the vapor to a middle plate of a distillation column for further concentration.

CONSTITUTION: In producing a concentrated solution of ethanol from a highly diluted aqueous solution of ethanol, especially a fermented solution prepared by continuous fermentation using a pervaporation device 2 having a pervaporation film of ethanol preference transmission type, vapor at the transmission side of the pervaporation film is collected by a condenser 3, fed to a middle plat of a distillation column 6, further concentrated. A feed solution at the primary side of the device 2 is preferably heated 7 by the vapor taken out from the top of the distillation column, condensed, partially refluxed from the distillation column 6 and the residual condensed solution is taken out as a product. Further preferably, a solution at the column bottom discharged from the distillation column 6 is subjected to heat exchange 5 with cooled condensed solution fed to the distillation column 6. The cooled condensed substance is preliminarily heated and fed to the distillation column 6 to give the concentrated solution in an industrial scale economically and advantageously.