An inkjet head which is provided with a nozzle plate that is covered with
a water repellent film including a Ni-PTFE film, and a plurality of
nozzles that are formed through the nozzle plate to eject ink. In this
structure, the nozzle plate is subjected to a heat treatment after the
Ni-PTFE film is formed on the nozzle plate, and then is subjected to
water cooling. The water cooling is performed using cooling water having
a temperature ranging from 15.degree. C. through 30.degree. C. after the
heat treatment is finished.