PURPOSE: To prevent the decline of smoke-removing effect caused by increase in smoke quantity and to maintain excellent smoke-removing effect for a long time, by arranging two corona discharge electrodes, which discharge only at one pointed end, in a prescribed direction and at a prescribed position in a cylindrical flow path provided with electrode plate at inside.

CONSTITUTION: Two corona discharge electrodes 4, 4 (needlelike, edgelike, or sawtoothlike electrodes), which discharge only at one pointed end 12, are arranged in a cylindrical flow path 2 for smoke etc., provided with electrode plate 1, along the axis of the flow path with said one end 12 directed to the inlet of the path, and with another end to the outlet side of the path. The apparatus is so constituted that l>r1+r2, where l is the distance between the pointed ends 12, 12, and r1, r2 are the distance of the pointed ends 12 from the electrode plate 1. Said path may have a section which is long side to side, or plural electrode may be arranged by conventional method. This apparatus exhibits no decline in smoke-removal effect unlike conventional method even when the quantity of smoke is increased.