An actuator includes: a diaphragm having a thickness equal to or greater than 0.5 μm and equal to or less than 20 μm; a piezoelectric body layer which is provided on a first surface side of the diaphragm, and receives stress from the diaphragm; a pair of electrodes which is provided on the first surface side of the diaphragm together with the piezoelectric body layer, and is mutually opposing via the piezoelectric body layer; and a stress adjusting layer which is provided on a second surface side of the diaphragm on an opposite side to the first surface of the diaphragm, and receives stress from the diaphragm in a same direction as the stress that the piezoelectric body layer receives from the diaphragm.