Abstract: A battery 2 includes: a container 10; and an electrode group 6 housed in the container 10 together with an alkaline electrolyte liquid 4. The electrode group 6 includes a nickel electrode 14 as a positive electrode and a negative electrode 12 that are combined with a separator 8 interposed therebetween. The nickel electrode 14 includes a positive electrode core and a positive electrode mixture permeated in the positive electrode core. The positive electrode mixture contains nickel hydroxide that is a positive electrode active material. The nickel hydroxide contains a sulfate salt, and a weight rate of a S component contained in the sulfate salt to a Ni component in the nickel hydroxide is 0.28% or more and 1.50% or less.