A multi-layer piezoelectric element having high durability which allows it
to increase the amount of displacement of a piezoelectric actuator under
high voltage and high pressure and does not undergo a change in the
amount of displacement during continuous operation in a high electric
field and under a high pressure over a long time period is provided.The
multi-layer piezoelectric element comprises a stack of at least one
piezoelectric layer and a plurality of internal electrodes consisting of
first and second internal electrodes placed one on another, a first
external electrode formed on a first side face of the stack and connected
to the first internal electrode and a second external electrode formed on
a second side face of the stack and connected to the second internal
electrode, wherein the bonding strength between the piezoelectric layer
and the internal electrode is weaker than the bending strength of the
piezoelectric layer.