A multi-nozzle ink jet head using piezoelectric elements and a manufacturing method thereof are disclosed. A head (1) has a nozzle member (10) in which a plurality of nozzles (12) are formed, a pressure chamber wall member (14) in which a plurality of pressure chambers (15) are formed, and piezoelectric type actuators that have a diaphragm (18) and a plurality of piezo elements (19) and apply pressure to each of the plurality of pressure chambers for ejecting ink from the nozzles. A rigid coating member (23, 25) is provided on inner surfaces of the pressure chamber walls or on parts of the diaphragm in contact with the pressure chamber wall member, thus increasing the rigidity of the pressure chamber walls.