An ink jet head comprising: a head chip having a size in a longitudinal direction and a size in a width direction which is perpendicular to the longitudinal direction and a size in a thickness direction which is perpendicular to the longitudinal direction and to the width direction, and comprising a plurality of drive walls and channels juxtaposed alternately in the longitudinal direction to form a channel array, an outlet and an inlet of the channels being arranged respectively at a front surface and a rear surface of the head chip in the thickness direction, and a drive electrode formed on each drive wall; a nozzle plate provided with a nozzle for ejecting ink, at a corresponding position to the channel on the front surface of the head chip; a connection electrode to electrically connect to the respective drive electrode, formed on the rear surface of the head chip; and a wiring board on which an electrode portion is formed for applying a voltage from a drive circuit to the respective drive electrode via the connection electrode, the wiring board being bonded to project from the head chip in the width direction perpendicular to the channel array direction and perpendicular in the thickness direction, wherein the ink jet head can eject the ink in the respective channel from the respective nozzle by applying the voltage to the drive electrode to cause a shear deformation on the drive wall, the ink jet head characterized in that it further comprises: a holding member disposed at a position covering the electrode portion to hold a portion of the wiring board projecting from the head chip; and an electrode portion protection member bonded between the holding member and the electrode portion by using adhesive, and having a thickness in the range of 0.01mm - 0.5mm at a part covering the electrode portion. a head chip having a size in a longitudinal direction and a size in a width direction which is perpendicular to the longitudinal direction and a size in a thickness direction which is perpendicular to the longitudinal direction and to the width direction, and comprising a plurality of drive walls and channels juxtaposed alternately in the longitudinal direction to form a channel array, an outlet and an inlet of the channels being arranged respectively at a front surface and a rear surface of the head chip in the thickness direction, and a drive electrode formed on each drive wall; a nozzle plate provided with a nozzle for ejecting ink, at a corresponding position to the channel on the front surface of the head chip; a connection electrode to electrically connect to the respective drive electrode, formed on the rear surface of the head chip; and a wiring board on which an electrode portion is formed for applying a voltage from a drive circuit to the respective drive electrode via the connection electrode, the wiring board being bonded to project from the head chip in the width direction perpendicular to the channel array direction and perpendicular in the thickness direction, wherein the ink jet head can eject the ink in the respective channel from the respective nozzle by applying the voltage to the drive electrode to cause a shear deformation on the drive wall, the ink jet head characterized in that it further comprises: a holding member disposed at a position covering the electrode portion to hold a portion of the wiring board projecting from the head chip; and an electrode portion protection member bonded between the holding member and the electrode portion by using adhesive, and having a thickness in the range of 0.01mm - 0.5mm at a part covering the electrode portion. a holding member disposed at a position covering the electrode portion to hold a portion of the wiring board projecting from the head chip; and an electrode portion protection member bonded between the holding member and the electrode portion by using adhesive, and having a thickness in the range of 0.01mm - 0.5mm at a part covering the electrode portion.