PURPOSE: To enhance the utilization factor of positive electrode active material, the discharge characteristics and the life of a battery by employing the aggregate of spherical particles mainly composed of nickel hydroxide including a specified %, Co by weight or one element out of specified element groups.

CONSTITUTION: Paste type positive electrode active material is maily composed of nickel hydroxide, and of the aggregate of spherical particles containing 1 to 10% Co by weight, or mainly composed of nickel powder hydroxide, 1 to 10% Co by weight, and of the aggregate of spherical particles including 1 to 10% of at least one kind of A element by weight. In this case, the A element shall be at least one kind selected out of the groups of In, Bi, Te, Ge, Tl, Sn, Sb, and Ga. When the aforesaid active material is formed into a paste shape, and is filled in a foamed nickel substrate and the like, it is formed into closest packing, so that the utilization factor of the active material is thereby enhanced. Moreover, the containment of the A element restrains nickel peroxide which is formed at the time of overcharging, from being collapsed, so that the charge/discharge cyclic life of the battery is thereby enhanced.