An ink jet head comprising: a plurality of first side walls (21a, 21b, 21c) including at least two piezoelectric elements; a plurality of second side walls (22a, 22b, 22c) including at least two piezoelectric elements, wherein the second side walls (22a, 22b, 22c) alternate with the first side walls (21a, 21b, 22c) along a first direction, the first side walls (21a, 21b, 21c) providing first side surfaces and the second side walls providing second side surfaces for driving pressure chambers (3a, 3b, 3c) and dummy pressure chambers (4a, 4b, 4c) in an alternating manner, the driving pressure chambers (3a, 3b, 3c) and the dummy pressure chambers (4a, 4b, 4c) including a first driving pressure chamber and a first dummy pressure chamber that are formed from a common first wall and having a volume bound by opposed first and second side wall surfaces, a base surface and a top surface; a first electrode on the base surface and the first side wall surface of the first driving pressure chamber; a second electrode (6a, 7a) on the first side wall surface of the first dummy pressure chamber; an ink chamber containing conductive ink and in fluid communication with the first driving pressure chamber; and a control unit characterized in that the control unit is configured to apply a first driving voltage pattern having a first waveform to the first electrode of the first driving pressure chamber which ejects the conductive ink, and to an electrode of a driving pressure chamber which does not eject the conductive ink, and a second driving voltage pattern having a second waveform, at least a portion of which is inverted with respect to the first waveform, to the second electrode (6a, 7a) to cause the conductive ink to be ejected from or supplied into the first driving pressure chamber, and cause the second electrode (6a, 7a) to electrically float such that the conductive ink is not ejected from or supplied into the first driving pressure chamber. a plurality of first side walls (21a, 21b, 21c) including at least two piezoelectric elements; a plurality of second side walls (22a, 22b, 22c) including at least two piezoelectric elements, wherein the second side walls (22a, 22b, 22c) alternate with the first side walls (21a, 21b, 22c) along a first direction, the first side walls (21a, 21b, 21c) providing first side surfaces and the second side walls providing second side surfaces for driving pressure chambers (3a, 3b, 3c) and dummy pressure chambers (4a, 4b, 4c) in an alternating manner, the driving pressure chambers (3a, 3b, 3c) and the dummy pressure chambers (4a, 4b, 4c) including a first driving pressure chamber and a first dummy pressure chamber that are formed from a common first wall and having a volume bound by opposed first and second side wall surfaces, a base surface and a top surface; a first electrode on the base surface and the first side wall surface of the first driving pressure chamber; a second electrode (6a, 7a) on the first side wall surface of the first dummy pressure chamber; an ink chamber containing conductive ink and in fluid communication with the first driving pressure chamber; and a control unit characterized in that the control unit is configured to apply a first driving voltage pattern having a first waveform to the first electrode of the first driving pressure chamber which ejects the conductive ink, and to an electrode of a driving pressure chamber which does not eject the conductive ink, and a second driving voltage pattern having a second waveform, at least a portion of which is inverted with respect to the first waveform, to the second electrode (6a, 7a) to cause the conductive ink to be ejected from or supplied into the first driving pressure chamber, and cause the second electrode (6a, 7a) to electrically float such that the conductive ink is not ejected from or supplied into the first driving pressure chamber.