Abstract: A metal catalyst carried on a carrier material is provided, the carrier material being selected from the group consisting of a powder of fine tourmaline crystals possessing polarity and a formed body containing a plurality of fine tourmaline crystals possessing polarity. The catalyst is prepared by immersing the carrier material in an aqueous solution containing at least one metal salt, mixing and stirring the aqueous solution until the at least one metal ion is deposited on poles of the tourmaline crystals of the carrier material, separating the carrier material from the aqueous solution, evaporating off traces of the aqueous solution from the carrier material, and drying the carrier material. The metal catalyst may be prepared by immersing the carrier material in an aqueous solution containing two or more metal ions, wherein the metal ions are deposited on said carrier material in an inverse proportion to the magnitude of the deposition ionization tendencies of the metal ions.