The ozone emitted from indoor air cleaners with corona chargers is harmful to the human respiratory system. In this study, a functional treatment of the discharge electrode surface was attempted to reduce the level of ozone generation from the corona discharge. The ozone emission level and charger performance were evaluated by measuring the particle removal efficiency and the pressure drop characteristics with the dust loading on the filter. Ozone production from the low-ozone discharge electrode was reduced by approximately 60% compared to conventional discharge electrode, but the corona initiating voltage and discharge current were equivalent to those of the conventional electrode. The particle removal efficiency of a low-grade filter assisted by the corona charger increased to a high-grade filter without a charger. The replacement time for the low-grade filter with the charger was approximately three times longer than that of a high-grade filter.