An object of the present invention is to provide a method capable of producing cycloalkanol and/or cycloalkanone with a favorable selectivity by oxidizing cycloalkane with a favorable conversion.A cycloalkanol and/or cycloalkanone are produced by oxidizing cycloalkane with oxygen in the presence of mesoporous silica which contains at least one metal selected from metals of Groups 5 to 10 of the Periodic Table and which is also subjected to a contact treatment with an organosilicon compound. The metal is preferably at least one metal selected from the group consisting of vanadium, chromium, manganese, iron, cobalt, ruthenium and palladium, and the mesoporous silica is preferably MCM-41 type mesoporous silica.