BATTERY PACK

A battery pack includes a battery stack including plural battery cells, a housing accommodating the battery stack, a heater substrate including plural metal patterns, and plural heat conduction sheets. The battery cells are arrayed in a thickness direction. The heater substrate is disposed inside the housing such that the metal patterns oppose the corresponding battery cells. The metal patterns generate heat when electrified. The heat conduction sheets are interposed between the corresponding battery cells and metal patterns.