PURPOSE: To suppress content of pollutant in an exhaust gas at a value which is remarkably lower than an allowable limit in a clean gas by collecting a fluid supplied in a second stage to top ends of collecting electrodes under the lower ends thereof, then discharging the fluid from a filter and feeding dry dust collected in the second stage to a dust receiving means.

CONSTITUTION: The liquid supplied in the second stage 2 to the top ends of the collecting electrodes 3b is collected under the lower ends of the collecting electrodes 3b, then is discharged from the filter in a horizontal direction and the almost dry dust further collected in the second stage 2 is fed to the dust receiving means 5b. By this constitution, pollutant in the exhaust gas is not blended with almost dry dust further collected in the second stage 2 and the pollutant together with the dust is not discharged from the filter. Consequently sludge which contains the pollutant sand is difficult to treat is not generated in the second stage 2. As the dust and the pollutant are suitably collected, content of the pollutant in the exhaust gas can be suppressed at the value which is remarkably lower than an allowable limit in the clean gas.