A liquid container for containing a liquid which is to be supplied to a liquid ejecting apparatus, comprising: a cap member, a bottom portion, a containing portion for containing the liquid and including a liquid out-flowing hole for out-flowing the liquid to an external portion and an air introducing hole for introducing external air into the containing portion, and a deforming portion (112, 114) being deformable in such a direction that a volume of the containing portion is reduced according to a decrease in an internal pressure of the containing portion; and an air introducing portion for opening and closing the air introducing hole, wherein the air introducing portion includes: a first sealing portion constituting the outer circumference of the air introducing hole inside the containing portion; a second sealing portion displaceably disposed inside the containing portion and capable of closing the air introducing hole by being pressed against the first sealing portion; and a biasing portion pressing the second sealing portion toward the first sealing portion, wherein the deforming portion (112, 114) includes: a rigid portion which is not deformed according to a decrease in an internal pressure of the containing portion; and a flexible portion which is deformed according to the decrease in an internal pressure of the containing portion to displace the rigid portion in such a direction that a volume of the containing portion is decreased, wherein the second sealing portion is disposed at such a position that the second sealing portion is not overlapped with the rigid portion when the rigid portion is projected in the displacement direction, and the air introducing portion further functioning as a transmitting portion, and the liquid container further comprises a transmitting portion which is installed to rotate about a supporting point and which is able to contact with the displaced rigid portion by a first arm portion with respect to the supporting point and is able to transmit the displacement to the second sealing portion by a second arm portion with respect to the supporting point so that the second sealing portion is separated from the first sealing portion, a spring biasing the rigid portion in such a direction that the capacity of the ink containing portion is increased. a cap member, a bottom portion, a containing portion for containing the liquid and including a liquid out-flowing hole for out-flowing the liquid to an external portion and an air introducing hole for introducing external air into the containing portion, and a deforming portion (112, 114) being deformable in such a direction that a volume of the containing portion is reduced according to a decrease in an internal pressure of the containing portion; and an air introducing portion for opening and closing the air introducing hole, wherein the air introducing portion includes: a first sealing portion constituting the outer circumference of the air introducing hole inside the containing portion; a second sealing portion displaceably disposed inside the containing portion and capable of closing the air introducing hole by being pressed against the first sealing portion; and a biasing portion pressing the second sealing portion toward the first sealing portion, a first sealing portion constituting the outer circumference of the air introducing hole inside the containing portion; a second sealing portion displaceably disposed inside the containing portion and capable of closing the air introducing hole by being pressed against the first sealing portion; and a biasing portion pressing the second sealing portion toward the first sealing portion, wherein the deforming portion (112, 114) includes: a rigid portion which is not deformed according to a decrease in an internal pressure of the containing portion; and a flexible portion which is deformed according to the decrease in an internal pressure of the containing portion to displace the rigid portion in such a direction that a volume of the containing portion is decreased, a rigid portion which is not deformed according to a decrease in an internal pressure of the containing portion; and a flexible portion which is deformed according to the decrease in an internal pressure of the containing portion to displace the rigid portion in such a direction that a volume of the containing portion is decreased, wherein the second sealing portion is disposed at such a position that the second sealing portion is not overlapped with the rigid portion when the rigid portion is projected in the displacement direction, and the air introducing portion further functioning as a transmitting portion, and the liquid container further comprises a transmitting portion which is installed to rotate about a supporting point and which is able to contact with the displaced rigid portion by a first arm portion with respect to the supporting point and is able to transmit the displacement to the second sealing portion by a second arm portion with respect to the supporting point so that the second sealing portion is separated from the first sealing portion, a spring biasing the rigid portion in such a direction that the capacity of the ink containing portion is increased.