Abstract: This invention relates to hydrous gel membranes for gas separation which comprise support membranes formed by solvent-soluble polymeric materials containing in their repeating unit a bulky structural part and hydrophilic functional groups represented by the following general formula (1) ##STR1## (R.sub.1, R.sub.2, R.sub.3, and R.sub.4 designate hydrogen, alkyl group, and halogen and R.sub.5 and R.sub.6 designate any one of --H, --SO.sub.3 H, --COOH, and --OH) and water or an aqueous solution of substances with affinity for CO.sub.2 substantially uniformly retained in the support membranes. The membranes show not only high CO.sub.2 permeation and CO.sub.2 selectivity but also long-term stable membrane performance and ease of fabricability into membranes and are capable of recovering a large volume of CO.sub.2 generated at stationary sites efficiently at low cost.