Provided is a liquid supply apparatus and a liquid ejection apparatus according to which liquid injected through a liquid injection portion can be supplied stably. The liquid supply apparatus includes: a liquid containing chamber capable of containing a liquid to be supplied to a liquid ejection portion; an air chamber in communication with the atmosphere; a communication path that allows an air introduction port for introducing air into the liquid containing chamber and an air chamber to be in communication, and a liquid injection portion through which the liquid can be injected into the liquid containing chamber. The liquid containing chamber is fixed such that the air introduction port is located at a bottom portion of the liquid containing chamber. The volume of the communication path is smaller than the volume of the air chamber. The uppermost portion of the communication path is located above the uppermost portion of the liquid containing chamber.