This exhaust gas purification catalytic device 100 includes: a substrate 10; at least one type of noble-metal catalyst PGM that is supported on the substrate 10; and a coating layer 15 on the surface of the substrate 10. The substrate 10 includes a plurality of cells 12 which are demarcated by porous walls 11. The substrate 10 and the coating layer 15 each include ceria-zirconia composite oxide particles CZ.