To suppress increase of a temperature caused by heating at the time of refreshing by arranging a plurality of filter blocks at intervals in a direction of exhaust gas flow, and refreshing by heating every filter block.
Particle materials stuck on a filter are burnt every filter block 14 simultaneously. As a result, a time for refreshing a filter is shortened. Since each filter block 14 is arranged at intervals 16 in a flow passage for exhaust gas, current-carrying of a heater 15 is carried out in each filter block 14 simultaneously, and the particle materials are burnt. Even the filter is refreshed, a position of a heating source owning to the combustion of the particle materials is dispersed by the intervals 16, and a time for burning the particle materials is only necessary to a time for burning the particle materials in one filter block. It is thus possible to suppress increase of a temperature in a low level, and it is also possible to prevent melting failure accident.
TAMATSU KOICHI
KOJIMA TADAYUKI
