A liquid supply unit is provided with a liquid supply part, an outer peripheral wall, contact portions and a positioning portion. When a plane including a portion in which the end portion of the outer peripheral wall abuts on a sealing member of a liquid ejection apparatus is referred to as a first reference plane, a direction orthogonal to the first reference plane is referred to as a Z axis direction, a direction orthogonal to the Z axis direction is referred to as an X axis direction, a direction orthogonal to the Z axis direction and the X axis direction is referred to as a Y axis direction, and a plane including the contact portions is referred to as a second reference plane, then, the positioning portion is positioned between the end portion of the outer peripheral wall and the contact portions in the X axis direction, the positioning portion is positioned between the end portion of the outer peripheral wall and the contact portions in the Z axis direction, and the second reference plane crosses the sealing member.