PURPOSE: To collect and remove harmful particles in tobacco smoke, etc. or harmful gas effectively by utilizing fins of finned heat exchanger as discharging electrode and arranging dust collecting electrodes corresponding to said discharging electrode.

CONSTITUTION: Fins of a finned heat exchanger are utilized as discharging electrodes 2 and dust collecting electrodes 3 are arranged corresponding to the discharging electrodes. Namely, electrical and mechanical dust collecting effect and ionic wind in accompany with corona discharge combined with electrostatic effect are generated utilizing fins of conventional heat exchanger to promote migration or diffusion of harmful particles or harmful gas to improve efficiency for absorption and removal of a dust collecting electrode for performing cleaning of gas.