Provided is a highly efficient method for the production of aldehydes and ketones, which is inexpensive, exhibits high reactivity, and is capable of easy separation of byproduct after the reaction. More particularly, there is provided a method for producing an aldehyde or a ketone, comprising at least an oxidation step of oxidizing a primary alcohol or a secondary alcohol in the presence of a polymeric carbodiimide represented by the following formula (1) and having a weight-average molecular weight of 300 to 5000, and a sulfoxide compound, together with an acid and a base, or together with a salt of the acid and the base.