BATTERY PACK

Provided is a battery pack including a rectangular parallelepiped first battery module having a first air intake surface, and a rectangular parallelepiped second battery module having a second air intake surface. A cooling air flow passage chamber is formed between the first air intake surface and the second air intake surface. The battery pack includes a one-side wall and an other-side wall that are interposed between the first air intake surface and the second air intake surface and seal the cooling air flow passage chamber from a third direction. The one-side wall and the other-side wall are formed so as to be able to expand and contract in a first direction while maintaining the cooling air flow passage chamber in a sealed state.