A UiO‐66 membrane was synthesized on an Al2O3 support by an in situ solvothermal method with a coordination modulation technique. We first confirmed the organic selectivity of the UiO‐66 membrane for methanol, ethanol, and acetone in mixtures with water. The membrane displayed highly stable pervaporation performance during the test and exhibited a separation factor of approximately 4.3 and a flux of 1.28 kg m–2 h–1 in ethanol/water. From the water and ethanol vapor adsorption measurement, the water uptake was lower in a binary system than that in a single system, although the ethanol uptake was similar for the binary and single systems. Therefore, the ethanol selectivity of the UiO‐66 membrane can be attributed to the preferential adsorption of the organic compound rather than water, as confirmed by a binary‐vapor adsorption measurement.