BATTERY PACK

A battery pack includes a battery module and a pack case. The battery module includes a plurality of cylindrical batteries each including, at one end in a specified direction, a battery exhaust valve that opens in response to an increase in internal pressure; and a battery holder including a plurality of housing parts for the one ends of the cylindrical batteries in the specified direction to be inserted. The pack case houses the battery module and internally includes an exhaust passage for gas exhausted from at least one of the plurality of cylindrical batteries to be exhausted out of the pack case. Each of the plurality of housing parts includes a lid part facing the battery exhaust valve of a corresponding cylindrical battery. The lid part includes an opening cover part that creates a larger holder opening with a greater outside diameter than the battery exhaust valve, and the opening cover part includes a ring-shaped or incomplete ring-shaped outer periphery that is defined by a weak part with less strength than a part external to the opening cover part.