An actuator 20 is prepared which comprises an ink pump section 29 made by forming a spacer plate 25 with a plurality of window portions 28 formed thereon, a closure plate 23 stacked on one side of the spacer plate 25 for covering the window portions 28 and a connection plate 24 stacked on the other side of the spacer plate 25 for covering the above window portions 28 respectively of ceramic green sheets in lamination to integrally fire them, and a piezoelectric/electrostrictive operating section 22 composed of electrodes 31, 33 and a piezoelectric/electrostrictive layer 32 on the outer surface of the closure plate 23. Thereafter, the actuator 20 is pasted to a holding adhesive film and the holding adhesive film is stripped from the actuator 20 after subjecting the actuator to a given inspection if necessary or to cutting into a given shape if necessary.; Subsequently the actuator 20 is heat-treated. Then, onto this actuator 20, an ink nozzle member 11 with a plurality of nozzle holes 12 is stacked and joined. The ink jet print head has a strong joining and an improvement in liquid resistance.