Abstract: A catalyst for reforming a hydrocarbon with steam has a platinum group metal deposited on a carrier having a volume of pores with pore sizes of 500 Angstroms or smaller being 0.15 ml per gram or greater, a volume of pores having pore sizes of more than 500 Angstroms being 0.14 ml per gram or smaller, and an average pore size being 90 Angstroms or greater. The platinum group metal specifically includes rhodium and ruthenium, and the carrier preferably includes zirconia and stabilized zirconia. As a promoter component, at least one metal of cobalt and manganese is used. The catalyst is high in catalytic activity and long in catalytic life.