PURPOSE: To make it possible to smoothly perform the jet flight of an ink droplet, by mounting an air buble trap chamber in an ink cartridge.

CONSTITUTION: An ink cartridge 2 for supplying recording ink to an ink jet recording apparatus is constituted from an ink receiving bag 3 made of a flexible material filled with ink 2 to be replenished, an enclosure 4 with a rigid structure for mounting said bag 3 therein, a cap member 5 fixedly provided to one opening part of said enclosure 4, an elastic member 6 for preventing the outflow of the ink 2 to be replenished filling said cap or the inflow of air from the outside and enabled in the insert and piercing of a hollow needle and a trap assembly 7 connected to the opening part of the ink receiving bag 3 in a hermetically sealed state at one end thereof while connected to the cap member 5 in an air-tight manner at the other end thereof and having an ink sump at the intermediate part thereof. The trap assembly 7 is constituted from an ink flowline 8 communicated with the ink receiving bag 3, a trap chamber 9 and an outlet flowline 10.