To provide an exhaust gas duct enabling miniaturization of the whole of equipment and reduction of the cost of installation by improving the cooling capacity and by shortening thereby a duct length on the occasion of cooling to a prescribed gas temperature.

In an exhaust gas duct 1 connected to an exhaust gas inlet of cooling equipment for cooling exhaust gas discharged from an electric furnace or the like, a plurality of fins 2 are provided on the inner surface of an exhaust gas channel of the exhaust gas duct 1 at prescribed intervals in the flow direction of the exhaust gas, while the exhaust gas duct 1 has a cooling box 4 which is fitted to an opening 3 provided in the flow direction of the exhaust gas at a prescribed position of the duct and makes a cooling medium flow through.