Abstract: Provided is a diesel engine which can efficiently regenerate a diesel particulate filter. The control for regeneration using an ECU includes a first regeneration by burning particulate matter at slightly more than 300° C. for 20 minutes when the accumulation of particulate matter exceeds a first threshold; a second regeneration by burning particulate matter at approximately 560° C. for 30 minutes by an additional injection to remove particulate matter other than ash when the accumulation of particulate matter exceeds the first threshold for a first predetermined period of time, or every 100 hours; and a third regeneration by burning particulate matter at approximately 600° C. for 15 minutes by an additional injection to remove particulate matter other than ash when the accumulation of particulate matter exceeds a second threshold and an emergency regeneration switch is pushed, or after 50 hours since the second or third regeneration and the emergency regeneration switch is pushed.