PURPOSE: To thoroughly wash the whole dust collecting part by arranging plural washing nozzles on the sides of a charged part and a dust collecting part and arranging the washing nozzles on the outflow side so that they may not be included in planes that are parallel to dust collecting electrode plates and include the washing nozzles on the inflow side.

CONSTITUTION: A dust collecting part 13 is formed of plural charge electrode plates 6 in parallel to an earth electrode plate 5, and plural dust collecting electrode plates 7 in opposite to the charge electrode plates 6 to form the electric field. On the inflow side of a charge part 2 and on the outflow side of the dust collecting part 3, plural washing nozzles 8a, 8b directed to the charge part 2 side and the dust collecting pan 3 side are arranged on planes parallel to the inflow face and the outflow face respectively. The washing nozzles on the outflow side 8 are arranged horizontally movably by 1/2L to the horizontal installing pitch L of the washing nozzles on the inflow side 8a so that they may not be included in planes that are parallel to the dust collecting electrode plates 7 and include the washing nozzles 8a on the inflow side.