PROBLEM TO BE SOLVED: To provide such a molding that its structure is changed according to the kind of gas in contact therewith to adsorb/separate the gas. SOLUTION: The molding for gas separation contains an organometallic complex which has a flexible, crystalline and mutually-fittable structure, and can have a first structure in the no presence of the gas having affinity and a second structure having high affinity to the gas in the presence of the gas having affinity, and is composed of a metal ion, an aromatic carboxylic acid polyvalent ligand and an aromatic bivalent ligand containing a nitrogen atom or a phosphorus atom. COPYRIGHT: (C)2010,JPO&INPIT