A denitration process for removing nitrogen oxides contained in low-temperature exhaust gas at a high denitration rate; namely, a denitration process for reductively removing nitrogen oxides contained in an exhaust gas (x) containing nitrogen monoxide and sulfur dioxide. The process comprises a preliminary step 2 of partially oxidizing nitrogen monoxide in the exhaust gas to form nitrogen dioxide, a radical formation step 3 of adding a nitrogen compound and a hydrocarbon compound to a high-temperature zone 22 to form amine radicals (r), and a denitration step 4 of mixing the amine radicals (r) with the pretreated gas (p) containing nitrogen monoxide and nitrogen dioxide that was discharged from the preliminary step 2. As a result, nitrogen oxides in the exhaust gas (x) are reductively decomposed.