Ink jet recording apparatus and ink container used for such apparatus

An ink jet recording apparatus comprises an ink jet recording head for discharging ink to enable ink to adhere to a recording medium for the formation of images, an ink container provided with an ink bladder to store ink to be supplied to the recording head, an ink supply path for supplying ink from the ink container to the recording head, a sub-container arranged on the ink supply path to retain ink from the ink container provisionally and supply the ink to the recording head. For this ink jet recording apparatus, the sub-container is provided with an ink inlet port for receiving ink from the ink container, and an ink outlet port for leading out ink to the recording head, a sub-ink bladder for forming a closed space with the exception of the ink inlet port and ink outlet port, and a case for covering the bladder, having at the same time a communicating portion with the outside, to protect the bladder in the closed space with the exception of the communicating portion, and provided further with a first open and close valve provided for the ink inlet port, a second open and close valve provided for the ink outlet port, and pressure adjustment means communicated with the communicating portion to be able to adjust the pressure in the space between the sub-ink bladder and the case, hence using ink in the ink container effectively for the stabilized output of images in higher quality.