Battery module and power storage system

According to one embodiment, a battery module includes a plurality of batteries, a case housing the batteries, a terminal plate, and a base member having an electrical insulating property. A circuit in which current flows through the battery is connected to a first connection position on the terminal plate, and an external terminal is connected to a second connection position away from the first connection position toward the outside in the first direction. The base member includes a bottom wall portion adjacent to the terminal plate from one side in a second direction intersecting the first direction, and a pair of side wall portions adjacent to the terminal plate from opposite sides in a third direction intersecting the first and second directions. A terminal plate is fastened to the bottom wall portion, and each side wall portion is fastened to the housing. 实施方式的电池模块具备：多个电池、收纳电池的壳体、端子板、以及具有电绝缘性的基座部件。在端子板上在第一连接位置连接有电流通过电池流动的电路，并在从第一连接位置向第一方向的外侧远离的第二连接位置连接有外部端子。基座部件具备：从与第一方向交叉的第二方向的一侧与端子板相邻的底壁部、以及在与第一及第二方向交叉