The object of the present invention is to provide a process capable of producing cycloalkanol and/or cycloalkanone in excellent selectivity by oxidizing cycloalkane in a good degree of conversion. The present invention relates to a process for producing cycloalkanol and/or cycloalkanone, which comprises oxidizing cycloalkane with oxygen at 25 to 140° C. in the presence of mesoporous silica containing the group 8 and/or 9 element in the periodic table, wherein the content of phosphorus atom in the mesoporous silica is 0 to 4 mol % based on silicon atom. Said element is preferably cobalt and said mesoporous silica is preferably MCM-41.