Abstract: Electrostatic precipitator is disclosed, including a discharge unit having ground electrodes and discharge electrodes, and a collecting unit having collecting electrodes and positive electrodes, wherein the discharge unit is applied of a voltage enough to emit a photo-energy which can activate a photo-catalyst, and a component in the electrostatic precipitator contains the photo-catalyst, or a separate photo-catalyst filter containing the photo-catalyst is provided within a reach of the photo-energy emitted from the discharge unit , thereby the photo-energy from the discharge unit activating the photo-catalyst, whereby providing a simple structured electrostatic precipitator making sterilization and deodorization at a low cost.