To provide a material, an element and a method for treating waste gas usable repeatedly by applying adsorption/desorption treatment to the waste gas simultaneously containing, for example, the basic material such as ammonia and the org. compd. such as hydrocarbon as subject material to be treated.

The treating material constituted by sticking a weakly acidic inorg. salt, for example, a phosphate compd., to a porous adsorbent, for example, hydrophobic zeolite, the treating element obtained by forming the treating material in a form like a honeycomb and the treating method having the stage for adsorbing/desorbing the waste gas containing the basic material by using these material or element are provided.