PURPOSE: To obtain a completely sealed storage battery which doesn't require any water supply by using a grid made of a lead-calcium alloy, and installing a device containing catalyst used for binding hydrogen and oxygen.

CONSTITUTION: A positive and a negative plate 2 are prepared by packing an active material into a lead-calcium alloy grid consisting of lead and 0.2wt% of calcium. A battery case 1 contains an electrolyte 4, and an assembled element 5 constituted by placing the positive plates 2 and the negative plates 2 alternately with separators 3 interposed between them. A porous case 10, which is made of ceramic and contains a catalyst body 9 that contains many catalyst grains and is used for binding oxygen and hydrogen, is installed in an upper space 8 of the battery case 1.