A nickel-hydrogen storage battery includes a positive electrode, a negative electrode using an AB5 based hydrogen-absorbing alloy, and a separator arranged between the positive and negative electrodes. The AB5 based hydrogen-absorbing alloy includes an A element, which is a constituent element of a misch metal, and a B element, which includes nickel and cobalt. The ratio of the amount of substance of the B element to that of the A element is 5.2 or more and 5.4 or less. The ratio of the amount of substance of cobalt to that of the A element is 0.15 or more and 0.4 or less. The liquid retention volume (V1) and the true volume (V2) of the separator, the theoretical capacity of the negative electrode (C1), and the theoretical capacity of the positive electrode (C2) satisfy the following expression. 2.0<=V1/V2*C1/C2<=3.1.