BATTERY PACK

PROBLEM TO BE SOLVED: To provide a battery pack with a plurality of batteries and superior in dimensional precision and mechanical strength even when a square type battery high in volumetric efficiency is used.SOLUTION: A battery pack includes: a battery group formed by electrically connecting a plurality of batteries by a connection member; holding means with which the plurality of batteries are mutually restrained; a protection circuit board which is connected to the battery group; and a resin-made sheath material which integrally covers the battery group, the protection circuit board and the holding means by filling a resin into a space of a molding mold in which the battery group, the protection circuit board and the holding means are housed and by curing it. The resin of the sheath material contains a heat absorbing agent formed of a compound exhibiting endothermic reaction.