To produce a conjugate unsaturated carbonyl compound under a mild condition in good production efficiency.

This method for producing the conjugate unsaturated carbonyl compound comprises reacting an unsaturated compound having a methylene group at the vicinal position of a carbon-carbon double bond with oxygen in the presence of a catalyst constituted of an imide compound represented by formula (1), wherein, R1 and R2 are each a hydrogen atom, a halogen atom, an alkyl group, an aryl group or the like, and can form a double bond or an aromatic or nonaromatic ring by binding to each other; X is an oxygen atom or a hydroxyl group and a cobalt (II) salt of an acid having pKa ≥8.0 to provide the objective corresponding conjugate unsaturated carbonyl compound having an oxo group introduced to the carbon atom of the methylene group. For example, a monocyclic or polycyclic compound having the carbon-carbon double bond in the ring can be used as the unsaturated compound having the methylene group at the vicinity position of the carbon-carbon double bond.