A plasma reaction apparatus and method applied to reformation of fuel by generating and using rotating arc plasma in a furnace, the chemical treatment of a persistent gas, and the apparatus for decreasing NOx by an occlusion catalyst. A raw material for a reaction is allowed to flow into the furnace through a hole, causing it to flow within the furnace in a continuous swirl. Furthermore, an expanded plasma reaction zone is provided by a wide area chamber which is formed on an upper part of the furnace and has a greater width than that of a lower part of the furnace, and thus a plasma being generated can be expanded by the expanded plasma zone and delayed from flowing out of the furnace by corners of the wide area chamber that is spaced from a plasma inducing electrode therein.