A battery pack of the present invention includes: a battery assembly including a plurality of batteries having a sealed portion, the plurality of batteries being connected to each other; a terminal portion electrically connected to the battery assembly and outputting electric power; and a composite layer structure including a heat-absorbing layer and a heat-conductive layer layered on the heat-absorbing layer, the composite layer structure being arranged at least at a part of a periphery of the battery assembly. The heat-absorbing layer has a specific heat of 1,000 J/kg·° C. or more. The heat-conductive layer has a heat conductivity of 10 W/m·K or more. This configuration allows for a small, light, and highly safe battery pack that is free from battery pack damage even when a battery in the battery pack has trouble and emits a high-temperature inflammable gas to expose the inside of the battery pack to a high-temperature environment.