Abstract: The present invention relates to an ink cartridge for an inkjet printer, the ink cartridge having a separate refilling port formed on the upper surface of a main body housing in which ink is stored and having mounted a port cover for opening and closing the refilling port, thereby enabling convenient refilling of ink through the refilling port by an individual user even without using a separate working tool or a specialized company for refilling ink. In addition, by having formed a display window for observing, with the naked eye from the outside, the amount of ink being refilled, the ink cartridge enables the user to easily perceive time for refilling ink. Also, by preventing the ink from being refilled too much or too little when the ink is being refilled, the ink cartridge enables refilling of an appropriate amount of the ink.