To provide a method for producing a carboxylic acid, capable of reducing the generation of by-products and environment-polluting substances in the production of the carboxylic acid, and a method for cleaving the bond of a carbonyl compound.

This method for generating the carboxylic acid and/or a ketone is provided by performing the reaction of the carbonyl compound with a vanadium-based catalyst in a carboxylic acid solvent under oxygen atmosphere to cleave the bond of the carbonyl compound.