BATTERY

Provided is a battery which is able to promptly release heat from a casing including a power generating element housed therein, and reliably prevent the occurrence of rapid thermal decomposition and the like of one of a positive electrode active material and an electrolyte from. In the battery including a positive electrode member, a negative electrode member, a casing, and a heat transfer plate, the heat transfer plate 30 is configured to have a region 30a in contact with the outer surface of the casing 20 and a region 30b provided with a joining material (double-sided tape 50a) for joining the heat transfer plate to the outer surface of the casing, thereby efficiently dissipating heat in the casing (outer casing) from the region 30a in direct contact with the outer surface of the casing. The region 30b of the heat transfer plate provided with the joining material serves as a step section at a level lower than the region of the heat transfer plate in contact with the casing. In addition, the region of the heat transfer plate provided with the joining material is used as through holes 32a, 32b, and the joining material filling the through holes bonds the heat transfer plate to the outer surface of the casing.