A step of forming a vibration plate includes a step of forming an insulation film in order to cause the surface roughness Ra of the insulation film to be in the range of 1 nm to 3 nm: the insulation film being made of zirconia which has been obtained by depositing a zirconium layer, and accordingly by the thermally oxidizing the zirconium layer at a predetermined temperature, and the insulation film constituting the uppermost surface of the vibration plate. In addition, a step of forming a piezoelectric elements includes: a step of applying titanium (Ti) onto a lower electrode by use of a sputtering method, and of forming a seed titanium layer thereon; and a step of forming a piezoelectric precursor film by applying a piezoelectric material onto the seed titanium layer, and of forming a piezoelectric layer by baking, and crystallizing, the piezoelectric precursor layer.