An ink container having an ink reservoir for storing ink, a cover set above the ink reservoir for forming an ink adjusting room with a top portion of the ink reservoir, an ink outlet for providing ink within the ink reservoir, and an elastic deformation device set within the ink reservoir. The elastic deformation device is connected to the gap of the ink reservoir to accept external air into the elastic deformation device. When a pressure within the ink reservoir is lower than a pressure of external air, the external air flowing into the elastic deformation device of the ink container causes the elastic deformation device to expand. When the pressure within the ink reservoir is higher than the pressure of the external air, the elastic deformation device shrinks to have an outwardly overlapping wall with a folding shape in order to balance the pressure of the external air with the pressure of the ink reservoir.