The challenge for the present invention is to provide a catalyst composition restrained from declining in performance over time in purifying an exhaust gas containing an organic compound a silicon compound, a catalyst containing the catalyst composition, and a method for producing the catalyst.This challenge is solved by using a catalyst composition containing zeolite added to precious metal-carried alumina, and the silicon resistance of the catalyst is improved greatly. The amount of acid of the zeolite added is preferably in the range of 0.4 mmol·NH3/g to 1.5 mmol·NH3/g.