A fire-extinguishing device for a wick ignition type oil burner adapted to discharge combustion gas to a room is disclosed which is capable of effectively removing bad odor generating materials contained in combustion gas produced during the fire-extinguishing operation to prevent the discharge of bad odor to a room. The fire-extinguishing device includes an actuation mechanism actuated with a wick actuating mechanism of an oil burner at the fire-extinguishing operation to lift a combustion cylinder construction of the oil burner and a combustion gas clarification mechanism which carries a catalyst thereon and is adapted to sealedly fit an upper portion of the lifted combustion cylinder construction therein so that combustion gas produced during the fire-extinguishing operation may be passed through the catalyst to remove, from the combustion gas, bad odor generating materials contained therein.