In an ink tank, a main ink chamber is contiguous to a sub ink chamber containing an absorption member, and an air communication hole is formed on the top of the sub ink chamber. The absorption member holds ink pressure constant by capillary attraction of the absorption member. First, ink in the sub ink chamber is consumed with consumption of ink. When ink is consumed in a predetermined amount, air passes through the absorption member and a meniscus forming portion to form bubbles, which then move to the main ink chamber. Ink pressure is held constant by surface tension of the meniscus forming portion. Even if ink remains in a small amount, the ink leading portion makes the meniscus forming portion wet for holding ink pressure.