Ink cartridge for ink-jet printing apparatus

When an ink cartridge is installed in a normal direction, the projection of a holder is first fitted into a recessed part of a cartridge in a process of push down, succeeding push down is enabled and an ink supply port is fitted to an ink supply needle, however, if an ink cartridge is installed in an improper state, the bottom hits on the projection formed so that it is wide and push down is interrupted. Hereby, the ink supply needle can be prevented from being damaged due to the installation in an improper direction of the ink cartridge.