Actuator, liquid discharge head, liquid discharge device, and liquid discharge apparatus

A liquid discharge head comprising:

• a deformable thin-film structure having a nozzle from which a liquid is dischargeable;
• an electromechanical conversion structure disposed at a periphery of the nozzle of the deformable thin-film structure;
• an insulating film covering the electromechanical conversion structure;
• a protective film over a surface of the insulating film, the protective film covering the surface of the insulating film and a surface of an electrode wiring connected to the electromechanical conversion structure;
• and
• an adhesion improving film disposed between the electrode wiring and the protective film,
• wherein the electromechanical conversion structure is formed directly on the deformable thin-film structure, which is a nozzle plate, and
• a thickness of the adhesion improving film is equal to or smaller than 10 nm.