PURPOSE: To prolong the period of time in which normal deodorizing function is maintained by positioning an electric charging part on the upper stream side of a flow of air and a dust collecting part on the downstream side, dividing the electric charging part into two parts and making voltage impressed on one of the parts variable.

CONSTITUTION: An electric charging part 1 composed of a discharge wire and flat platelike electrodes 3 is positioned on the upper stream side of a flow of air and a dust collecting part 5 on the downstream side. The electric charging part 1 is divided into two parts and voltage impressed on the discharge wire 2' of one of the parts is made variable. Ozone is generated by raising voltage impressed on the discharge wire 2', a foul odor is decomposed with the ozone and the period of time in which normal deodorizing function is maintained can be prolonged.