GAS SEPARATION METHOD

Provided is a method for separating a specific gas from a raw gas using a gas separation membrane module that includes a gas separation membrane element enclosed in a housing. The element includes a gas separation membrane including a hydrophilic resin composition layer. The method includes: preparing the module; increasing pressure in an interior of the module; increasing a temperature in the interior; and feeding a raw gas to the interior. The layer of the module prepared is adjusted to contain moisture, and a moisture content thereof is an amount that allows an equilibrium relative humidity at a temperature of 23° C. of a gas phase portion in the housing to be 10% RH or more. The raw gas feeding step is performed after the preparation step. The pressure increase step and the temperature increase step are performed after the preparation step and before the raw gas feeding step.