PURPOSE: To obtain a three-component catalyst having excellent purifying characteristics by making the specific region on a monolithic carrier support three- catalytic components of the catalyst for purifying an exhaust gas.

CONSTITUTION: As the catalyst for purifying an exhaust gas, an A component comprising oxide of cerium, iron or the like, a B component comprising oxide of nickel, manganese or the like and a C component comprising platinum, rhodium or the like are supported by a monolithic carrier but the A component is supported at the upstream side of the carrier against the exhaust gas, the B component at the downstream side thereof and the C component is supported over the whole thereof. By this supporting arrangement, by the combination of the A and the C components and the combination of the B and C components, harmful components in the exhaust gas can be removed simultaneously and an excellent three- component catalyst is obtained.