The present invention provides a catalyst suitably employed in a variety of hydrocarbon reforming processes and a hydrocarbon reforming process including employing the catalyst in production of hydrogen or synthesis gas. The hydrocarbon reforming catalyst of the present invention contains an alumina carrier containing cerium oxide and, carried on the carrier, component (a), component (b), and optional component (c), the component (a) being at least one platinum group element selected from among ruthenium, platinum, rhodium, palladium, and iridium; the component (b) being cobalt and/or nickel, the component (c) being an alkaline earth metal. When steam reforming, autothermal reforming, partial-oxidation reforming, or carbon dioxide reforming of hydrocarbons is performed through employment of the catalyst, hydrogen or synthesis gas can be produced.