Abstract: Provided are zeolite comprising a metal and an oxygen-activated metal complex, wherein the above oxygen-activated metal complex is included within a unit cell comprised in the above zeolite as well as a gas decomposition agent comprised of the above zeolite. Examples of the above oxygen-activated metal complex are phthalocyanine metal complex, a bis(salicylidene)-o-phenylenediamidinato metal complex and a metal complex comprising a cyclic tetrapyrrole compound as a ligand. Examples of metal of the above oxygen-activated metal complex are silver, copper, zinc, platinum, palladium, cobalt, iron, manganese, ruthenium and the like. The above gas decomposition agent has an effect capable of continuously decomposing gases that are harmful to the health or felt unpleasant by human.