In the present invention, an electrode terminal 50 of a battery 1 includes: a first connection part 50a that encloses one side in an axial direction of an annular groove portion 23 provided in a circumferential wall of the battery 1; a second connection part 50b that encloses another side in the axial direction of the groove portion 23; and a bridge portion 50d that connects the first connection part 50a and the second connection part 50b. When the swelling of the battery 1 causes the groove portion 23 to expand in the axial direction, the bridge portion 50d ruptures and thereby blocks a current flowing between the first connection part 50a and the second connection part 50b.
