PURPOSE: To remove offensive odors with high efficiency by the procedure in which an alkali metal salt is added to a raw carbon material, then the mixture is subjected to a carbonization-activation treatment to obtain an alkali metal-containing activated carbon, and offensive odor components-containing gas is then brought into contact with the alkali metal-containing activated carbon.

CONSTITUTION: The salt of an alkali metal, e.g., K2SO4, etc., or an organic salt of alkali metal, e.g., CH3COONa, etc., is added to an activated carbon raw material, e.g., brown coal, etc.. Then, the mixture is subjected to a carbonization at 400 to 850°C and then to an activation treatment at 700 to 1100°C in a current of O2, CO2, H2O, or combustion gas in order to prepare an alkali metal-containing actuvated carbon. Then, a gas containing one or more S compounds of H2S, COS, mercaptans, sulfides, etc., is brought into contact with the alkali metal- containing activated carbon at 0 to 250°C, preferably 5 to 150°C, to remove the S compound by adsorption. In addition, the relative humidity of gas to be treated is regulated to 10 to 90 %, and also the moisture in the alkali metal-containing activated carbon is regulated to 5 to 50 wt %.