A non-oxidation heat treatment system having internal Rx gas (endothermic gas) generator includes: a heat treatment furnace whose internal environment kept to an atmosphere of an Rx gas; internal reformers for accommodating reaction catalysts for generating the Rx gas; material supply means for mixing raw gas as a material for generating the Rx gas and air to a given ratio to supply the mixture to the internal reformers; heating means disposed in the heat treatment furnace to heat an internal temperature of the heat treatment furnace to a temperature needed for annealing; and a controller disposed on the outside to control the internal temperature of the heat treatment furnace through the control of the ON/OFF and combustion loads of the of the heating means, wherein the internal reformers are loaded to the interior of the heat treatment furnace and the heating means includes regenerative type radiant tube burners.