An ink cartridge for supplying an ink to an ink jet type recording head is made of a paper box formed with an ink chamber. Inner wall surfaces of the ink chamber are processed to have water-repellency. The ink chamber is partitioned into a storage chamber storing the ink and an ink absorbent chamber containing an ink absorbent made of unwoven fabric. An ink outlet is formed in a bottom wall of the ink chamber. The ink outlet may be formed as a thin wall part with no water-repellency, so the ink percolates through the thin wall part. An ink run-out detection window is formed in the storage chamber. The ink run-out detection window may be a thin wall part or consist of an opening and a translucent paper sheet covering the opening.