a piezoelectric substrate grinding step of grinding a lower surface of the piezoelectric substrate, the lower surface being opposite to an upper surface on which the ejection grooves and {HEAD ~ the non ejection grooves} are formed, to allow {TAIL ~ the non ejection grooves} to penetrate the piezoelectric substrate from the upper surface through the lower surface thereof 
are formed to allow
a piezoelectric substrate grinding step of grinding a lower surface of the piezoelectric substrate , the lower surface being opposite to an upper surface on which the ejection grooves and { HEAD ~ the non ejection grooves } are formed , to allow { TAIL ~ the non ejection grooves } to penetrate the piezoelectric substrate from the upper surface through the lower surface thereof
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