A process for producing a zeolite membrane comprising a seed crystal forming step of placing, in a pressure-resistant vessel, a seeding sol containing silica, water and a structure-directing agent and a support in a state that the support is immersed in the seeding sol and heating the heat-resistant vessel to form a zeolite seed crystal on the surface of the support, and a membrane formation step of allowing the zeolite seed crystal to grow to form a zeolite membrane on the surface of the support. In the seed crystal forming step, the molar ratio of water/silica in the seeding sol is set 10 to 50 and the heating of the pressure-resistant vessel is conducted at 90 to 130° C. The crystal c-axis of the present zeolite membrane is oriented in a direction vertical to the surface of the support and its thickness is uniform.