To provide an extremely reliable liquid droplet ejection head by enhancing the etching resistance of a joined surface between a first substrate and a second substrate.

In the liquid droplet ejection head 1, the second substrate 9 having a pressured liquid chamber 6 communicating with a nozzle hole 2 of the first substrate 3, and a common liquid chamber 4 for supplying ink to the pressured liquid chamber 6, and provided with a piezoelectric element 7 and a diaphragm 8 generating liquid droplet ejection energy for ejecting ink from the nozzle hole 2 for the ink with which the pressured liquid chamber 6 is filled, and a third substrate 12 having a common liquid supply channel 11, communicating with a liquid supply through-hole 10 to which the ink is supplied from the outside and also communicating with the common liquid chamber 4 are joined to be layered. The head 1 is provided with a protective layer 19 to cover a range including at least the joined surface C of the second and third substrates 9 and 12 which are joined on an inner wall side of the common liquid chamber 4 and the common liquid supply channel 11 which communicate with each other.