The present invention makes it possible to effectively prevent a deterioration in the performance of an oxidation catalyst and thermal degradation of an SCR catalyst by carrying out temperature increase control whereby sulfates are removed. The invention is provided with: a first oxidation catalyst (31) that is provided in an exhaust system (16) of an internal combustion engine (10) and oxidizes HC; a selective reduction catalyst (41) that is provided in the exhaust system downstream of the first oxidation catalyst (31) and reduces and purifies a nitrogen compound in the exhaust using NH3 generated from urea water as a reducing agent; and a temperature increase control unit (62) capable of implementing temperature increase control whereby at least sulfates having accumulated on the first oxidation catalyst (31) are removed by supplying HC to the first oxidation catalyst (31) to increase the exhaust temperature.
