FIGS. 4A to 4D are perspective views showing the ink cartridge according to the embodiment of the invention, in which FIG. 4A is a diagram viewed in a direction where a diagonally upward back surface can be seen, FIG. 4B is a diagram viewed in a direction where a diagonally downward front surface can be seen, FIG. 4C is a diagram viewed in a direction where a diagonally downward back surface can b