To provide a furnace gas circulation unit capable of being arranged in an optional position of a furnace body without being positionally restricted to control the internal circulation or stirring of a furnace gas.

The furnace gas circulation unit 1 comprises first and second heat accumulation devices 2A:2B having supply and exhaust ports 20, respectively, a circulating fan 4 for pressurizing the furnace gas after cooling and feeding the resulting furnace gas to the supply and exhaust ports through the heat accumulation devices, and supply and exhaust switching valve devices 3A:3B switchable to a leading position or an injection position. Each of the heat accumulation devices comprises a heat accumulation body 21. The heat accumulation body receives heat by the heat transfer contact with the furnace gas to cool the furnace gas, and also radiates the heat by the heat transfer contact with a re-introduced flow to heat the re-introduced flow. The re-introduced flow of substantially the same direction is continuously injected to a specific part of furnace region by the plurality of supply and exhaust ports 20.