A liquid container has a movable member which defines a liquid containing space and which is displaced as the liquid is supplied, a valve for allowing a gas to be introduced into the containing space from the outside and for preventing the liquid from being extracted from the containing space to the outside, and an introduction channel for coupling the valve and the containing space to guide the introduced gas into the containing space. An intake port of the introduction channel located on the containing space side is positioned in an upper part of the containing space in an orientation in use. A negative pressure is kept substantially constant to consume the liquid completely. Since the air introduction for keeping the negative pressure at an adequate value is carried out in a region in a gaseous phase in the container, no leakage of ink occurs, and air is reliably introduced.