A safety valve (13) is integrally formed on a battery lid (3) together with a peripheral wall portion (14) by a press or the like. The safety valve (13) is formed connecting the peripheral wall portion (14), at the bottom of a recess portion (18) depressed from the upper surface (12a) of the base (12) of the battery lid (3). The upper surface (13a) of the safety valve (13) is positioned below the lower surface of the base (12). When a pressing force (X) parallel to the upper surface (13a) of the battery lid (3) acts while a coupling pipe or the like is connected to the inner peripheral surface (14a) of the peripheral wall portion (14), the pressing force (X) can be supported by the entire thickness (T) of the base (12) (plate thickness).
