A process for producing a carbonyl compound corresponding to an olefin, the process comprising reacting the olefin with molecular oxygen in a water-containing liquid phase comprising a palladium catalyst, a vanadium compound, and a heteropoly acid having a heteropoly anion represented by the Formula: [XaMbM′cOd]n− wherein X is any of elements selected from P, Si, and S; a represents an integer of 1 or 2; M and M′ represent any of elements selected from Mo, W, V, Ta, and Nb; b and c represent an integer of 0 or more; d represents an integer of 1 or more; and n represents an integer of 1 or more.