A lead-acid battery improving the charge acceptance in an initial stage, suppressing the decrease of the charge acceptance for a long time use of the battery and having a long life is provided. In a lead-acid battery using a paste type negative plate prepared by filling a past form negative active material using a lead powder as a starting material in a collector made of a lead alloy, a flake graphite and a condensate of bisphenols and aminobenzene sulfonic acid are contained in the negative active material. The average primary particle diameter of the flake graphite is 10 μm or more and 220 μm or less, preferably, 100 μm or more and 220 μm or less. The content of the flake graphite is preferably from 0.5 mass parts to 2.7 mass parts and, more preferably, from 1.1 mass parts to 2.2 mass parts based on 100 mass parts of the negative active material (spongy metallic lead) in a fully charged state.