The purpose/objective of the present invention is to make it possible to efficiently remove saturated hydrocarbons even in a gasoline engine wherein the exhaust gas temperature is low, while also making it possible to efficiently remove exhaust gas components other than the saturated hydrocarbons such as aromatic hydrocarbons and unsaturated hydrocarbons. An exhaust gas purifying catalyst device according to the present invention is arranged in an exhaust gas passage of an engine, and has a plurality of catalyst layers. This exhaust gas purifying catalyst device contains at least Pt as a catalyst metal, and the Pt is supported by silica-alumina that serves as a supporting material. The Pt-supporting silica-alumina, wherein Pt is supported by silica-alumina, is contained in a catalyst layer that comes into contact with an exhaust gas first.