To provide a method and an apparatus for synthesizing a zeolite membrane having a surface the condition of which is selectively controllable by controlling the synthesizing condition of the zeolite membrane.

The method of synthesizing the zeolite membrane includes a membrane forming process for membrane forming using a synthetic apparatus provided with a pressure control means while controlling a pressure condition in a hydrothermal synthesis for synthesizing A type or T type zeolite membrane on a supporting body. The synthetic method is performed by using the apparatus for synthesizing the zeolite membrane which has a synthetic vessel in which a hydrothermal synthesis is carried out to form the A type or the T type zeolite membrane on the supporting body, the pressure control means for controlling the pressure in the synthetic vessel and a heating means for heating the synthetic vessel.