There are provided a method of producing a carbonyl compound by a flow type reaction, including introducing a triphosgene solution into a flow channel (I), bringing the triphosgene solution into contact with a solid catalyst immobilized in at least a part of the flow channel (I) to generate a phosgene solution while the triphosgene solution is flowing through the flow channel (I), joining the phosgene solution and an active hydrogen-containing compound solution that flows inside the flow channel (II), which are subsequently allowed to flow downstream inside a reaction flow channel to be reacted in a presence of a tertiary amine, and obtaining a carbonyl compound in a joining solution; and a flow type reaction system that is suitable for carrying out this production method.