A method oxidizes an organic compound with oxygen in the presence of a catalyst, in which the catalyst contains a N-hydroxy- or N-(substituted oxy)-imide compound derivable from at least one selected from a target product, a reaction intermediate, and a reaction byproduct, and the catalyst is produced from at least one component selected from the target product, reaction intermediate, and reaction byproduct each formed as a result of the reaction and is used in the oxidation reaction so as to make up for a loss of the catalyst due to denaturation in the reaction. The method can easily and inexpensively make up for a loss of the catalyst denaturated in the course of reaction.