To provide a lead storage battery in which the deformation of a lattice hardly occurs even by manufacturing a plate group by a cast-on strap forming method and which has excellent overcharge lifetime performance.

The lead storage battery comprises an expanding lattice having an upper mask, a current collecting lug provided at the mask, and a reinforcing part continued to the lug as a wide width part of the upper mask. In this battery, a relation of z<x+y≤2z is satisfied, in the case of z1+z2=z, wherein x is a width of the current collecting lug, y is a distance from the starting point of the reinforcing part to the lug, z1 is a width of the measure of lattice beams connected to the upper mask, and z2 is a length of a nodal part of the lattice beams connected to the mask.