To provide a battery cooler capable of preventing ventilation resistance of a cooling air, and leading a wiring from respective battery modules to the external device such as a control device in space saving.

A rotation axis 32 of a blast member 30 exists between heights of both end parts of the upper and the lower directions of a module assembly 1, and in the blast member 30, a range of a lateral direction of the cooling air is made nearly over the whole region of the module assembly 1 regarding the aligning direction X. A wiring unit 55 is installed at a side face of the respective battery modules 1. The wiring unit 55 forms a passage in which a wiring 27 pulled out from inside the respective battery modules 1 is arranged.