To provide an electrostatic actuator, etc. which is capable of miniaturizing the size, and preventing moisture, etc. from entering a gap in an effective manner. An electrostatic actuator includes an electrode substrate 10 having individual electrodes 12 as fixed electrodes, and a cavity substrate 20 having diaphragms 22 as movable electrodes which are disposed so as to be opposed to the fixed electrodes 12 with a predetermined distance, and operated due to an electrostatic force occurring between the cavity substrate 20 and the individual electrodes 12. Sealing portions 26a are formed on one of the electrode substrate 10 and the cavity substrate 20, each of the sealing portions 26a has a plurality of sealing layers (a TEOS layer 25a, a moisture permeation preventing layer 25b) laminated one another, and each of the sealing layers is made of a sealing material 25 for isolating a space formed between the individual electrode 12 and the diaphragm 22.