A battery device designed so that a plurality of battery modules (1) are arranged in rows at given spaces in a enclosure (2). Turbulence accelerators (5), such as dummy battery units or the like, are provided in a position on the uppermost-stream side of the enclosure in which air flows in the direction of arrangement of the battery modules. The heat transfer ability for the battery modules in the upper-stream position is enhanced by the turbulence accelerators which disorders the airflow introduced into the enclosure. Auxiliary coolant intake ports (7) for the introduction of a coolant are provided in the middle of an airflow path, whereby the heat transfer ability on the lower-stream side is enhanced, so that battery temperature differences between the battery units arranged in the enclosure can be restrained. Thus, a simple-construction battery device is realized enjoying improved quality and operation stability.