Disclosed is an alkaline storage battery comprising: a positive electrode comprising nickel hydroxide; a negative electrode; and an electrolyte layer interposed between the positive electrode and the negative electrode. The electrolyte layer comprises a water absorbent polymer and an aqueous alkaline solution. The water absorbent polymer is obtained by saponification of a copolymer comprising 100 parts by weight of monomer (A) and 0.01 to 10 parts by weight of monomer (B). The monomer (A) has at least one group capable of being converted to a carboxyl group by saponification and has one polymerizable double bond, and the monomer (B) has two or more polymerizable double bonds.