The present invention is a catalyst comprising one or more kinds of catalyst metal, a promoter metal composed of at least one element selected from alkaline earth metals, transition metals, rare earth metals, aluminum and gallium, and a support, wherein the catalyst metal and the promoter metal are supported on the support through allowing a multi-element metal colloid solution to be attached to the support, and the multi-element metal colloid solution comprises a solvent comprising water or a mixture of water and an organic solvent, metal cluster particles which are dispersed and suspended in the solvent and composed of one or more kinds of catalyst metal, a protective agent for protecting the metal cluster particles, and one or more kinds of metal ions bonded to the protective agent, the ions selected from alkaline earth metal ions, transition metal ions, rare earth metal ions, aluminum ions and gallium ions.