A piezoelectric actuator is provided, including a piezoelectric layer which is joined to a joining member and which has a coefficient of linear expansion smaller than a coefficient of linear expansion of the joining member; a first electrode which is arranged on one surface of the piezoelectric layer; a second electrode which is arranged on a portion of the one surface of the piezoelectric layer different from the first electrode and which is in conduction with the first electrode; and a low dielectric layer which is formed between the piezoelectric layer and the second electrode and which has a dielectric constant lower than a dielectric constant of the piezoelectric layer.