A liquid ejection apparatus includes a tank; a liquid ejection head; and a casing configured to integrally cover the tank and the liquid ejection head. The tank includes a container portion configured to contain a liquid, an air introducing path arranged to introduce the air into the container portion, an inlet port configured to pour the liquid into the container portion, and an outlet port formed to supply the liquid into the liquid ejection head. In an attitude that the liquid is ejectable from the liquid ejection head, the liquid is contained in the container portion such that a liquid level of the liquid in the container portion is located at a higher position than a nozzle of the liquid ejection head in a vertical direction. In the attitude that the liquid is ejectable from the liquid election head, the inlet port is covered by the casing.