A one-way valve, a valve unit assembly and ink cartridge using this valve or valve unit assembly for controlling ink flow are disclosed. The one-way valve includes a foot support portion, a wall support portion projecting at an angle from an interior side of the foot support portion, a shoulder support portion bending towards an interior side of the wall support portion, and a head support portion projecting from a shoulder support portion with a through hole. The valve unit assembly includes a bottom cover with a through hole for holding the one-way valve, a pressing cover with a through hole, and an elastic one-way valve disposed between the bottom cover and the pressing cover. The pressing cover is maintained selectively in contact with the head support portion through hole by a pressure difference. The one-way valve and the valve unit assembly are disposed in an ink chamber to replace a porous member usually used in the ink chamber. As a result, the ink cartridge using the one-way valve can store more ink and remaining ink is handled in a more environment friendly manner.