Catalyst device for exhaust gas purification method and exhaust gas purification

A catalytic exhaust gas purification device 1 comprises Pt, Pd and Rh as the catalytic metals. The catalytic metal Pt is loaded on silica-alumina, which serves as support, and which is obtained by loading the Pt on silica-alumina, Pt-loaded silica-alumina, is contained in a catalytic layer to which an exhaust gas first into Contact comes.