Abstract: To provide a metal-based structure or nanoparticles whose homogeneity is not deteriorated and whose sticking formation is easy, and a production method thereof with a high safety. A metal-based structure comprises a hydrogen compound, cluster, or an aggregate thereof, represented by the general formula: MmH. The M is a metal-based atom. The m is an integer of 3 or more and 300 or less. H is a hydrogen atom.