Piezoelectric actuator, liquid transporting apparatus, and liquid-droplet jetting apparatus

A piezoelectric actuator which applies a pressure to an object, comprising:

• a vibration plate;
• a piezoelectric layer arranged on one surface of the vibration plate;
• a supporting member supporting the vibration plate and the piezoelectric layer, the supporting member having a relief portion which is long in a predetermined longitudinal direction and which releases a deformation of the vibration plate and the piezoelectric layer, and a joining portion which is arranged to surround the relief portion and is joined to one of the vibration plate and the piezoelectric layer;
• and
• a first electrode and a second electrode which are arranged on both surfaces of the piezoelectric layer respectively, each of the first and second electrodes being arranged at an area facing the relief portion;
• wherein a bending-stiffness lowering portion is formed in one of the vibration plate and the piezoelectric layer at a first area facing one end of the relief portion in the longitudinal direction;
• and
• wherein a first bending stiffness of the bending-stiffness lowering portion is lower than a second bending-stiffness of an other portion of the one of the vibration plate and the piezoelectric layer in which bending-stiffness lowering portion is formed, at a second area facing one end of the relief portion in a width direction orthogonal to the longitudinal direction.