An ink cartridge comprising: a case including an ink delivery path; an ink accommodating unit provided in the case and configured to accommodate ink therein; a moving body configured to move relative to the case; a single detecting unit provided to the case and configured to output a signal corresponding to a position of the moving body relative to the case; and a storing unit in which time length data indicative of a prescribed length of time is stored, wherein the ink delivery path has an ink delivery opening at one end and that is in fluid communication with the ink accommodating unit at another end; and the moving body is provided in the ink delivery path such that the moving body is movable in the ink delivery path, the moving body being configured to move relative to the case by being pushed by a hollow tube that is configured to enter the ink delivery path from the ink delivery opening to take up ink, the detecting unit outputs a signal indicative of a first prescribed value when the moving body reaches a first position defined in the case, and outputs a signal indicative of a second prescribed value different from the first prescribed value when the moving body reaches a second position different from the first position, characterized in that the ink cartridge further comprises: a controller configured to exchange signals with a control unit in a recording device, thereby allowing either the controller or the control unit to i) calculate a length of time taken by the value of the signal to change from the first prescribed value to the second prescribed value and to ii) compare the calculated length of time with the prescribed length of time indicated by the time length data stored in the storing unit. a case including an ink delivery path; an ink accommodating unit provided in the case and configured to accommodate ink therein; a moving body configured to move relative to the case; a single detecting unit provided to the case and configured to output a signal corresponding to a position of the moving body relative to the case; and a storing unit in which time length data indicative of a prescribed length of time is stored, wherein the ink delivery path has an ink delivery opening at one end and that is in fluid communication with the ink accommodating unit at another end; and the moving body is provided in the ink delivery path such that the moving body is movable in the ink delivery path, the moving body being configured to move relative to the case by being pushed by a hollow tube that is configured to enter the ink delivery path from the ink delivery opening to take up ink, the detecting unit outputs a signal indicative of a first prescribed value when the moving body reaches a first position defined in the case, and outputs a signal indicative of a second prescribed value different from the first prescribed value when the moving body reaches a second position different from the first position, characterized in that the ink cartridge further comprises: a controller configured to exchange signals with a control unit in a recording device, thereby allowing either the controller or the control unit to i) calculate a length of time taken by the value of the signal to change from the first prescribed value to the second prescribed value and to ii) compare the calculated length of time with the prescribed length of time indicated by the time length data stored in the storing unit. a controller configured to exchange signals with a control unit in a recording device, thereby allowing either the controller or the control unit to i) calculate a length of time taken by the value of the signal to change from the first prescribed value to the second prescribed value and to ii) compare the calculated length of time with the prescribed length of time indicated by the time length data stored in the storing unit. i) calculate a length of time taken by the value of the signal to change from the first prescribed value to the second prescribed value and to ii) compare the calculated length of time with the prescribed length of time indicated by the time length data stored in the storing unit.