The displacement as an actuator or the sensitivity as a sensor of a piezoelectric element can be increased and, in addition, the electric power consumption can be reduced by providing a thin film of potassium-sodium niobate, which is a perovskite type compound represented by a general formula ABO3, as a piezoelectric layer, wherein a crystal orientation of a crystal structure of potassium-sodium niobate has in-plane fourfold symmetry as a whole piezoelectric layer, where a first axis of rotational symmetry is a thickness direction of the piezoelectric layer.