The liquid filling method is for filling a liquid into a liquid discharge apparatus comprising a nozzle which discharges a droplet of the liquid, a pressure chamber which is in communication with the nozzle and is filled with the liquid to be discharged as the droplet through the nozzle, and a pressure generation device which generates pressure variation in the liquid inside the pressure chamber to cause the droplet to be discharged through the nozzle, and the method comprises the steps of: adjusting a contact angle of the liquid on an inner surface of the pressure chamber to be not more than an angle formed inside the pressure chamber by two mutually adjacent surfaces constituting the inner surface; and filling the liquid into the pressure chamber.