Disclosed herein is a heat exchange system that controls the temperature of a medium- or large-sized battery pack including a plurality of unit cells. The heat exchange system includes a sealed type housing surrounding the outer surface of the battery pack such that a predetermined flow channel, through which a heat exchange medium flows, is defined between the housing and the battery pack, a driving fan mounted in the housing for driving the heat exchange medium to flow, and a heat exchange unit mounted at one side of the housing for controlling the temperature of the heat exchange medium. In the heat exchange system according to the present invention, the heat exchange medium, for example, air is not introduced from the outside of the battery system, but is circulated in the battery system by the heat exchange unit. Consequently, the present invention has the effect of accomplishing the reduction in size of the battery system, reducing influences caused by external conditions, decreasing noise, and effectively controlling the optimum operating temperature of the battery pack.