An object of the present invention is to provide a method capable of producing a cycloalkanol and/or a cycloalkanone with a favorable selectivity coefficient by oxidizing a cycloalkane with a favorable conversion ratio.Disclosed is a method for producing a cycloalkanol and/or a cycloalkanone, which comprises oxidizing a cycloalkane with oxygen in the presence of a mesoporous silica which contains at least one transition metal and has been also subjected to contact treatment with an amine and/or ammonia. Preferably, a crystal obtained by mixing a compound containing the metal, a silicon compound, a structure-directing agent and water is subjected to contact treatment with an amine and/or ammonia and then fired to obtain a mesoporous silica, and a cycloalkane is oxidized with oxygen in the presence of the mesoporous silica.