Combustion appliance with safety device

A combustion appliance with a safety device therein, comprising a combustor composed of an inner flame cylinder with a plurality of small holes therein, a red-heat cylinder disposed on the outer side of said inner flame cylinder, an outer cylinder disposed on the outer side of said red-heat cylinder, and means for supplying combustable fuel between the inner flame cylinder and the red-heat cylinder, an oxygen sensor disposed in the flame rear flow of said combustor and in a position where the air excess ratio of said flames varies substantially depending on the amount of air available to combust fuel from said fuel supplying means, and a fuel feed cutting-off means for cutting off fuel supplied by said fuel supplying means with the output of said oxygen sensor, said oxygen sensor comprising a partial oxygen pressure sensitive oxygen sensor having a pair of spaced electrodes, the resistance between which varies with the partial oxygen pressure being detected.