Safety device for sealed battery and sealed battery with same

A safety device for a closed battery capable positively preventing a rupture due to a rapid internal pressure rise at over-packing and short-circuiting and being produced inexpensively, a positive electrode lid (16) attached to one end of an outer covering can (11) comprises a pressure receiving plate (18) forming the innermost lid and connected to positive electrode (13) of an electrode unit (12) via positive electrode lead (17), a shielding plate (20) forming a middle lid and electrically connected to the pressure receiving plate (18) via a center contact (19), and a sealing plate (21) forming the outermost lid and electrically connected to the shielding plate (20). The center contact (19) is formed of a projection (28) having a first flat contact surface (27) of the pressure receiving plate (18) and a second flat contact surface (29) of the shielding plate (20), and a plurality of annular grooves (31, 33) are alternately provided around the second flat contact surface (29) so as to face each other at 180 DEG intervals, the annular grooves (31, 33) being covered with a metal foil (34) to form valve membranes (35, 36).