PURPOSE: To provide a solid air cleaning agent which can cleans air while utilizing humidity of the air only by setting the agent in space whose capacity is limited and which is polluted with various kinds of pollutant gases with different chemical properties such as acidic, basic, or neutral properties and to provide a method to use the agent.

CONSTITUTION: A composition comprising (A) calcium carbonate, sodium di carbonate, or the like, (B) citric acid, succinic acid, or the like, (C) sodium sulfate, sodium salt of oxyacid of phosphorus, or the like, and (D) a water absorbable polymer compound as essential components is put in an air-permeable container or bag and set in space, wherein any components are anhydrous salts.