A new thin film heater for thermal print heads was developed. The thin film heater includes a resistor portion and a conductor portion that supplies voltage to the resistor. The resistor portion has a thin insulating self-oxidizing coat, which prevents oxidation and electrolytic corrosion by ink, so the thin film heater does not require a thick overcoat. The anode side of the conductor is covered with an ink barrier layer, so electrolytic corrosion is prevented. Furthermore, a print head structure that does not generate cavitation was developed, and it was shown that the thin film heater could be used in this print head. The heater requires remarkably little energy to eject ink droplets. Also, the heater rapidly heats up the ink, which translates into more uniform velocity of ejected ink droplets.