An ink cartridge includes a container; an ink reservoir provided in the container; an opening provided in the container, the opening being situated in the container so that the opening can communicate with the ink reservoir through a fluid path; and a stop fitted in the opening, the stop having elasticity and being formed of a material such that a hollow needle can be penetrated through the stop. The stop is moveable between a first position permitting communication between the opening and the fluid path, and a second position in which the stop substantially obstructs communication between the opening and the fluid path.