PURPOSE: To prevent a self discharge characteristic and deterioration of a life, by improving the liquid tightness in a junction part between cells to prevent internal short circuit of a lead storage battery.

CONSTITUTION: A thickness part 6 is provided to a connection part between cells in the upper part of a battery jar partition 4, while saw tooth shaped protrusion parts 7 are provided to surfaces, located at a face-to-face position to said part 6, of junction parts 3 in the upper part of a strap 2, after the part 6 is previously heated to increase temperature by a hot jet or the like, the parts 3 in the upper part of the strap 2 are forcibly contacted under pressure by a press machine or the like to intrude the parts 7 into said part 6 and weld the parts 3 to each other of the neighboring cells. Then a part in the vicinity of the parts 3 is coated by an oxidation resistant synthetic resin 5. The connection part between the cells obtained in such way is provided with the parts 7 to the parts 3 in the upper part of the strap 2 to both lengthen a route path between the neighboring cells and eliminate dislocation of the parts 3 by biting of the parts 7 into the part 6 of the partiton 4, while the resin 5 moves around the bottom part of the part 6 to quite eliminate a liquid bypass.