PURPOSE: To facilitate suppression of extension of an active material for negative electrode plates which are shaped into expanded lattices and to improve cycle life characteristics of a battery by forming bumps on inner wall surfaces which face end surfaces of separators in a battery jar.

CONSTITUTION: A group of electrode plates 3 are disposed in the center of each space room 2 which is formed by a partition part 1a in a threecell type battery jar 1. This battery is composed of the following units: a positive electrode plate 4, separators 5 which are disposed on both sides of this positive electrode plate 4 and made of glass fiber containing an electrolytic solution, and negative electrode plates 6 which are disposed outside these separators 5, 5 and shaped into expanded lattices. Guide ribs (bumps) 7 are disposed up and down on both-sided inner wall surfaces 1b and 1c, which face side end surfaces 5a of the separators 5, in the battery jar 1, that is, the space room 2. Extension of an active material on the side of the negative electrodes, which extends from the negative electrodes to the side of the positive electrode, is suppressed by the bumps, so that side shorting is prevented from occurring. Hence, cycling life of the battery can be much improved.