under in between and outer catalytic layers 2 3 and 4 was formed was dipped in a mixture of a dinitro diamine platinum solution and a barium acetate solution so as to be impregnated with 6 g l pt and 30 g l ba and then dried 150 u00b0 c for two hours and sintered at 500 u00b0 c for two hours in order to assess nox conversion efficiency and anti sox poisoning property of the exhaust gas purifying catalyst as an example of the invention a comparative sample exhaust gas purifying catalyst was prepared by simply replacing the a 3 ce u2014 zr composite oxide with a ce u2014 zr composite oxide having a zr molar fraction of 0 2 i e ce 0 8 zr 0 2 o 2 which is hereafter referred to as an a 1 ce u2014 zr composite oxide or a ce u2014 zr composite oxide having a zr molar fraction of 0 9 i e ce 0 1 zr 0 9 o 2 which is hereafter referred to as an a 4 ce u2014 zr composite oxide in the exhaust gas purifying catalyst described above impurities content of each of the example exhaust gas purifying catalyst according to the above embodiment and the comparative exhaust gas purifying catalyst was less than one weight the relationship between zr.