A method of injecting a liquid into a liquid container detachably mounted on a liquid consuming device, the liquid container comprising: a liquid containing chamber (370) containing the liquid; a liquid supply port (50) connectable to the liquid consuming device; a liquid guide path for guiding the liquid contained in the liquid containing chamber to the liquid supply port; an air communicating path (150) communicating the liquid containing chamber with air and having a communicating passage portion (360) that is narrower than at least a part of other communicating paths in the air communicating path and can store some liquid contained in the liquid containing chamber by a meniscus; and a liquid residual quantity sensor (31) provided in the liquid guide path for outputting different signals in accordance with a residual amount of the liquid in the liquid containing portion, wherein the liquid contained in the liquid containing chamber can be blocked from the air by the liquid stored in the communicating passage portion, the method comprising: forming an injection port (601) on a more upstream side than an upstream end of the communicating passage portion (360); injecting a predetermined amount of liquid from the injection port; and sealing the injection port after injecting the liquid.