PURPOSE: An exhaust gas purification device is provided to completely oxidize HC and CO included in the exhaust gas by mounting a DOC unit between a CPF unit and a SCR unit. CONSTITUTION: An exhaust gas purification device comprises a smoke reducing unit(30), a diesel oxidation catalyst(40), a blow nozzle(50) and an optional catalytic reduction unit(60). The smoke reducing unit oxidizes hydrocarbon and carbon monoxide included in the exhaust gas using a first diesel oxidation catalyst. The smoke reducing unit collects and reproduces the particulates. The diesel oxidation catalyst is installed in the backend of a CPF unit and oxidizes HC and CO using a second DOC. The diesel oxidation catalyst oxidizes the nitrogen oxide to nitrogen dioxide using second DOC. The blow nozzle is established at the DOC unit backend and spays the reducing agent on the exhaust gas from the DOC unit. The optional catalytic reduction unit is installed the backend of the blow nozzle and restores the nitric oxide within the exhaust to the nitrogen gas.