Abstract: An ink cartridge has a flexible ink bag that stores ink and undergoes expansion and contraction movement in accordance with fluctuations in the amount of ink stored. The ink bag is accommodated in a housing and has an ink inlet port for supplying ink into the ink bag and an ink outlet port for discharging stored ink. An inflow port and an outlet port are formed in a front surface of the housing for connection to the ink inlet port and ink outlet port, respectively, of the ink bag. First and second detection windows are formed on respective first and second opposite side surfaces of the housing. A plate member is mounted on the ink bag for movement therewith in response to fluctuations in the amount of ink stored in the ink bag. The plate member has a protruding portion that closes the second detection window during movement thereof to detect the full state of the ink bag.

Abstract: To be capable of preventing the erroneous detection of the residual amount of ink, and to facilitate exchange work.