There is provided a method for producing trifluoroamine oxide. The method includes a step of preparing an intermediate product by simultaneously providing and reacting nitrogen trifluoride and nitrous oxide under the presence of a SbF.sub.5 reaction activator; and a step of producing trifluoroamine oxide by reacting the intermediate product with potassium fluoride. The step of reacting the intermediate product with potassium fluoride is performed under atmospheric pressure and room temperature.