A battery pack includes: a plurality of battery cells arranged in a line in one arrangement direction; a pair of end plates disposed at opposite ends of the plurality of battery cells in the arrangement direction; a pair of binding bars disposed on opposite sides of the plurality of battery cells in a direction perpendicular to the arrangement direction; and an insulator disposed in a gap between each of the binding bars and the battery cells. The insulator having an initial thickness larger than a thickness of the gap before insertion of the insulator into the gap in a compressed state. The end plates sandwich the battery cells therebetween in the arrangement direction, and the binding bars sandwich the battery cells therebetween in the direction perpendicular to the arrangement direction.