Provided is an integrated heat exchanger including a header tank in which a gasket is interposed between the header and the tank to seal a portion that the header and the tank are coupled to each other, wherein an inner space of the header tank is partitioned such that a first space portion formed between regions in which the heat exchange medium flows is formed to be in communication with an external region of the header tank through a heat exchange medium discharging means formed at a portion that the header and the tank are coupled to each other, thereby preventing the heat exchange mediums from being leaked between two heat exchange portions and to detect a leakage of the heat exchange medium even when the leakage of the heat exchange medium occurs.