Disclosed is an exhaust gas purifying catalyst, which comprises a CeZr-based composite oxide capable of maintaining a hollow structure to ensure an oxygen absorbing/releasing capability, even after being exposed to high-temperature exhaust gas. The exhaust gas purifying catalyst comprises a honeycomb-shaped substrate, and a catalyst layer formed on a surface of the substrate. The catalyst layer contains a composite oxide which includes cerium (Ce) and zirconium (Zr) and has a hollow structure, and a catalytic metal supported by the composite oxide. The composite oxide having the hollow structure includes, in a state after being subjected to a thermal aging in Air at 1000° C. for 24 hours, a particle with a shape having an outer diameter of 750 to 1000 nm and a shell thickness of 80 to 120 nm.