A filter (30) traps particulate matter in an exhaust gas. A filter inlet side pressure sensor (34) is provided in an inlet side of the filter (30). An EGR valve inlet side pressure sensor (22) is provided in an inlet side of an EGR valve (20). A regeneration controller (38C) determines whether or not the filter inlet side pressure sensor (34) is in failure based upon a difference between a pressure value detected by the filter inlet side pressure sensor (34) and a pressure value detected by the EGR valve inlet side pressure sensor (22). When the filter inlet side pressure sensor (34) is in failure, the regeneration controller (38C) performs control of regeneration treatment using a differential pressure calculated based upon a pressure value detected by the EGR valve inlet side pressure sensor (22) and a pressure value detected by the filter outlet side pressure sensor (35).