A liquid ejection device actuator unit is fitted to a nozzle unit including a liquid chamber of which an inside volume is variable by deformation of a liquid chamber side diaphragm and an ejection tube which ejects a liquid from the liquid chamber. The liquid ejection device actuator unit includes a movable plate which comes into contact with the liquid chamber side diaphragm, a piezoelectric element which comes into contact with the movable plate at one end of the piezoelectric element in an expansion or contraction direction to deform the movable plate, and a support member which is adhered to the piezoelectric element at other end of the piezoelectric element in the expansion or contraction direction. At least one of a contact portion of the movable plate and the piezoelectric element and a contact portion of the piezoelectric element and the support member is adhered by a hard material containing adhesive in which a hard material with a larger elastic modulus than a hardened adhesive is mixed.
