PURPOSE: To stably atomize an ink flow jetted out of a nozzle by a method wherein an exciting current for vibrating an electromechanical conversion element mechanically connected to the nozzle varies with an unsymmetrical amplitude.

CONSTITUTION: Pressurized ink (including paint) supplied to a nozzle 1 is continuously jetted out of a nozzle hole 2. An electromechanical conversion element 3 mechanically connected to the nozzle 1 vibrates in the axial direction of the nozzle. The element 3 is preferably a stack of a plurality of piezoelectric elements. An exciting power source 6 preferably supplies an alternative current having a symmetrical amplitude to at least one of the piezoelectric elements and an electric current of half-wave rectification waveform to at least one of the other elements. In this manner, as a whole, the element 3 vibrates with an unsymmetrical waveform obtained by synthesizing the two waveforms. Therefore, after being jetted out, an ink flow is powerfully atomized at a small distance from the nozzle hole 2, and the cutting distance is stabilized. In addition, there is no occurrence of satellite. This device especially takes effect with the use of paint.