A particulate filter regenerating device is configured to prevent the uneven distribution of particulate matter that results from interruption of the regeneration process and protect the particulate filter. The frequency with which regeneration is executed is increased by determining that it is time to regenerate the particulate filter at a time t1 when the exhaust gas temperature Texhin has reached or exceeded a prescribed temperature Texh1. Additionally, particulate filter regenerating device determines that it is time to regenerate the particulate filter when the quantity of accumulated particulate matter reaches or exceeds a prescribed value PM1. The particulate filter is regenerated by raising the temperature of the exhaust gas and combusting the accumulated particulate matter.