In case of emergency regeneration, i.e., any one of forced regeneration after a judgment is made that purification is insufficient in purification judgment after ending forced regeneration, forced regeneration after time has expired before completing of forced regeneration, or forced regeneration when the pressure difference across a DPF exceeds a predetermined first judging pressure difference under a state where the traveling distance of a vehicle is shorter than a predetermined distance for judgment, an alarm for urging manual regeneration is issued. When manual regeneration is designated thereafter, manual regeneration is performed, and, when predetermined conditions are satisfied without the reception of a designation of manual regeneration, automatic regeneration is performed. In forced regeneration of the DPF for purifying PM in exhaust gas, forced regeneration is performed surely even if manual regeneration is not selected at the time of emergency regeneration, and convenience is enhanced by reducing burden on a driver.