A method of manufacturing an actuator including an ink pump section made by forming a spacer plate with a plurality of window portions formed therein, a closure plate stacked on one side of the spacer plate for covering the window portions and a connection plate stacked on the other side of the spacer plate for covering the above window portions. These plates are formed as laminated ceramic green sheets that are later fired to form an integrated body. A piezoelectric/electrostrictive operating section composed of electrodes and a piezoelectric/electrostrictive layer is then formed on the outer surface of the closure plate. Thereafter, the actuator is pasted to a holding adhesive film and the holding adhesive film is stripped from the actuator after subjecting the actuator to a given inspection, if necessary, or to cutting into a given shape, if necessary. Subsequently, the actuator is heat-treated. Then, onto this actuator, an ink nozzle member with a plurality of nozzle holes is stacked and joined. The ink jet print head has a strong adhesive joint between the actuator and the ink nozzle member and improved liquid resistance.