A liquid sensing apparatus includes a liquid sensing chamber 33 having a liquid inlet port that is in communication with an external liquid container in which a liquid is reserved, and a liquid outlet port that is in communication with a liquid consuming apparatus, a movable member 34 movable depending on a liquid level in the liquid sensing chamber 33, a recess portion 33b, 41a for cooperating with a wall surface of the movable member 34 to form a closed space when the movable member 34 is moved to a predetermined position depending the liquid level, and a piezoelectric sensing means 40 for applying a vibration to the recess portion and sensing a state of a free vibration following upon the vibration.