The back pressure of an ink tank is controlled. A porous body is arranged inside the ink tank, the lower end of the porous body contacts an ink, and the ink ascends inside the porous body due to a capillary force. The upper end of the porous body is not immersed in the ink, and a maximum ascending force acts upon the ink stored in the ink tank. Therefore, the ink does not leak from a discharge head located lower than the ink tank. Further, because the ink is accumulated under the porous body and the amount of the ink contacting the porous body is small, components of the ink are less susceptible to deterioration.