A CO removal catalyst of inducing CO shift reaction for allowing water and carbon monoxide to react to produce hydrogen and carbon dioxide, comprising a catalyst carrier having a cerium-zirconium composite oxide and a zirconium oxide and a predetermined noble metal supported on the catalyst carrier, wherein the average particle diameter of the particulate cerium-zirconium composite oxide is greater than the average particle diameter of the particulate zirconium oxide, the average particle diameter of the particulate zirconium oxide is greater than the average particle diameter of the predetermined particulate noble metal and the predetermined noble metal is supported on the catalyst carrier more in the outer part thereof.