A method of injecting a liquid into a liquid container detachably mounted on a liquid consuming device, the liquid container including; a liquid containing portion; a liquid supply portion connectable to the liquid consuming device; a liquid guide passage for guiding the liquid contained in the liquid containing portion to the liquid supply portion; an air communicating passage communicating the liquid containing portion with an air; a first inner wall surface; and a second inner wall surface intersecting with the first inner wall surface, the first inner wall surface having a liquid containing portion outlet formed close to the second inner wall surface and allowing the liquid containing portion to communicate with the liquid guide passage, the method including: forming an injection port communicating with the liquid containing portion in the air communicating passage; injecting a predetermined amount of liquid through the injection port; and sealing the injection port after injecting the liquid.