Provided is a catalyst composition using other metals different from noble metals as a catalytic activity component and which has an excellent catalytic activity even after a thermal duration treatment. Provided are an exhaust gas purifying catalyst composition which includes ceria-zirconia particles with a feature in that a peak arising from (111) plane is divided into two peak tops in an XRD pattern and in which a transition metal including at least one of Cu, Cr, Fe, Mn, Co, Ni, and Ag is supported on the ceria-zirconia particles, and a catalyst using the exhaust gas purifying catalyst composition.