An ink jet head for compressing ink in an ink chamber to eject a drop of the ink from a nozzle. Ink compressing means for compressing the ink in the ink chamber by expanding and contracting in response to a voltage applied thereto is made of a piezoelectric high molecular substance. The ink compressing means comprises a single thin film of polyvinylidene fluoride (PVDF) or two PVDF films bonded together in a bimorph structure. Multiple nozzles are arranged in a predetermined direction. The PVDF film expands and contracts in a direction parallel to the direction of arrangement of the multiple nozzles.