A battery includes a casing made of metal; and a safety valve made of a thin plate. The casing includes a vent hole that provides communication between the inside of the battery and the outside of the battery. A seal member made of synthetic resin is provided between the peripheral edge portion around the vent hole and the peripheral edge portion of the safety valve. The seal member connects the peripheral edge portion around the vent hole to the peripheral edge portion of the safety valve such that the peripheral edge portion around the vent hole does not contact the peripheral edge portion of the safety valve.