An electrostatic ink-jet head (1) in which the present invention is applied comprises a pressure chamber (6) communicating with an ink nozzle (21), and an atmospheric pressure chamber (12) opened to the atmosphere, with a vibrating plate (5) being provided on the base plane of the pressure chamber (6). Voltage applied between the vibrating plate (5) and an electrode (43) causes the vibrating plate (5) to vibrate due to electrostatic force, thereby discharging ink droplets. A vibrating chamber (41) communicates with a pressure compensating chamber (49), and a displacement plate (16) capable of being displaced in the direction outward from the plane according to fluctuations in the external, atmospheric pressure is formed at the base plane of the pressure compensating chamber (49). Displacement of the displacement plate (16) increases/decreases the volume of the pressure compensating chamber (49), and the internal pressure of the vibrating chambers (41) communicating thereof is adjusted to match the external atmospheric pressure. Accordingly, the vibration properties of the vibrating plate (5) can be maintained constant even when the external atmospheric pressure fluctuates, and proper ink droplet discharging action can be maintained.