An exhaust gas purification catalyst device having a substrate, a first catalyst coating layer on the substrate, and a second catalyst coating layer on the first catalyst coating layer. The first catalyst coating layer includes inorganic oxide particles, palladium carried on the inorganic oxide particles, and a barium compound. The second catalyst coating layer includes alumina particles and rhodium carried by the alumina particles. The ratio (MBa/MRh) between the mass (MBa) of barium in the first catalyst coating layer and the mass (MRh) of rhodium in the second catalyst coating layer is 5.0-60.0 inclusive.