Fecha de publicación: 05/01/2023 Fuente: Wipo Milk or dairy products The purpose of the present invention is to provide a method for highly purifying a condensable product in a membrane reactor, the method being capable of enhancing the substance amount ratio of one condensable product, which is in the largest amount among the condensable products that have permeated to the permeation side of the membrane reactor, thereby highly purifying the condensable product. A method for highly purifying a condensable product in a membrane reactor according to the present invention comprises: a synthesis reaction step in which two or more condensable products are synthesized by introducing a starting material gas that contains a hydrogen gas and at least one of a carbon monoxide gas and a carbon dioxide gas into a first space of a membrane reactor that is provided with a separation membrane, the first space on the non-permeation side, the first space being filled with a synthesis catalyst, and a second space on the permeation side; a membrane separation step in which the condensable products produced in the first space in the synthesis reaction step are separated by being caused to permeate into the second space through the separation membrane; and a decomposition reaction step in which the condensable products permeated into the second space are decomposed by the action of a decomposition catalyst, thereby enhancing the substance amount ratio of one condensable product, which is in the largest amount among the permeated condensable products.