Abstract: In a combustion appliance with a safety device therein, an inner flame cylinder, a red-heat cylinder and an outer cylinder disposed concentrically on the outer side of the red-heat cylinder are provided to constitute a combustor and an oxygen sensor is disposed in the rear flow of the combustion flames of the combustor and in a position where the air excess ratio of the flames can be detected. During the incomplete combustion through air feed shortage or the like caused due to dust clogging or the like as well as during the oxygen depression, the oxygen sensor can detect changes in the flames or changes in the red-heat condition of the red-heat cylinder to stop the burning operation thereby to secure the safety.