PURPOSE: To raise dust collecting efficiency and to prevent rescattering in case of hammer hitting, by forming a dust collecting part by providing mixedly in parallel with a metallic cylindrical rod body, and an opening rod body having a channel-shaped section, which has opened toward the inflow direction of gas.

CONSTITUTION: When high voltage by which a dust collecting part 2 becomes positive is applied between an electric discharge part 1 and the dust collecting part 2, a nonuniform electric fiels is generated between both of them, and corona discharge is generated between the tip of a needle-like piece 4 of a discharge electrode 5 and a cylindrical body 6 of the dust collecting part 2. In this state, dust contained in gas is charged in a charged part in which corona discharge is generated, is sucked into the dust collecting part 2, and is caught. In this case, in the dust collecting part 2, a vortex is generated in the downstream side of the cylindrical body 6, and in the opening of an opening rod body 7, and the downstream side, therefore, dust is sucked satisfactorily, also since the opening rod body 7 can utilize its inside and outside surfaces, its utilized surface area is increased, the dust collecting efficiency is elevated, and scattering dust in case of hammer hitting is decreased.