A lead-acid battery includes a positive electrode plate, a negative electrode plate, and an electrolyte solution. The positive electrode plate includes a positive current collector and a positive electrode material. The negative electrode plate includes a negative current collector and a negative electrode material. The positive current collector contains a lead alloy containing Ca and Sn. The content of Ca in the positive current collector is 0.2% by mass or less, and the content of Sn is 0.5% by mass or more. The negative electrode material contains a first organic expander (excluding a lignin compound) containing at least one selected from the group consisting of a unit of a monocyclic aromatic compound and a unit of a bisphenol S compound.