A thermal oxidation decomposition type detoxifying apparatus for an exhaust gas comprises: an exhaust gas introducing conduit to introduce exhaust gas; a reactive unit to which said exhaust gas introducing conduit being connected and having a first reactive chamber kept at a first temperature and a second reactive chamber kept at a second temperature different from the first temperature, said second reactive chamber being disposed in downstream of and adjoined on said first reactive chamber; an oxidizing gas source adapted to supply an oxidizing gas into said first reactive chamber, said oxidizing gas undergoing thermal oxidation decomposition of said exhaust gas; a neutralizing gas source adapted to supply a neutralizing gas into said second reactive chamber, said neutralizing gas neutralizing a gas generated by the thermal oxidation decomposition; and a discharging unit to discharge a processed exhaust gas processed in said reactive unit. A thermal oxidation decomposition type detoxifying method for an exhaust gas, comprises: introducing an exhaust gas in a reactive unit having a first reactive chamber kept at a first temperature and a second reactive chamber kept at a second temperature different from the first temperature, said second reactive chamber being disposed in downstream of and adjoined on said first reactive chamber; supplying an oxidizing gas into said first reactive chamber, said oxidizing gas undergoing thermal oxidation decomposition of said exhaust gas; supplying a neutralizing gas into said second reactive chamber, said neutralizing gas neutralizing a gas generated by the thermal oxidation decomposition; and discharging a processed exhaust gas processed in said reactive unit to exterior of the reactive unit.