To provide a nickel-hydrogen secondary battery in which decrease in the operation voltage can be minimized during discharge while enhancing the utilization rate of a positive electrode active material.

The nickel-hydrogen secondary battery comprises a positive electrode 24 and a negative electrode 26. The positive electrode 24 has the positive electrode active material powder of nickel hydroxide particles 36, and a positive electrode additional material 38 distributed into the positive electrode active material powder and containing at least one kind selected from a group of Y, Yb, Er and their compounds. The negative electrode 26 has the powder 44 of a hydrogen storage alloy 44, and a negative electrode additional material 46 distributed into the powder 44 of the hydrogen storage alloy, and containing at least one kind selected from a group of Bi, In and their compounds.