An electrostatic atomizer includes a discharge electrode, an opposite electrode positioned in front of the discharge electrode in a spaced-apart relationship therewith, a housing for defining an atomization chamber between the discharge electrode and the opposite electrode, a water supply unit for supplying water for atomization to the discharge electrode, and a voltage application unit for applying a voltage to the discharge electrode. The housing is provided with an air vent window through which the atomization chamber is opened laterally outwards. The opposite electrode is provided with a soundproof shield portion extended therefrom to cover, when seen from a front side of the opposite electrode, the space existing laterally outwards of the air vent window of the housing. The soundproof shield portion reflects rearwards a discharge sound generated in the atomization chamber.