PURPOSE: To increase the porosity of a substrate and to increase the capacity density of an alkaline battery by specifying the volume ratio of carbonyl nickel powder in slurry and by specifying sintering temperature in the manufacture of the substrate.

CONSTITUTION: Nickel slurry comprising 2-6 volume % carbonyl nickel powder and an aqueous solution of an organic polymer such as carboxymethylcellulose is applied onto both sides of a porous metal core, and dried. They are sintered in a nonoxidizing atmosphere at 800-950°C and a sintered nickel substrate whose porosity is as high as 90-95% can be obtained. An active material is filled in the substrate obtained and an electrode for alkaline battery with high capacity density can be obtained. If the volume % of carbonyl nickel is less than 2%, no sinter is obtained, and if sintering temperature is 1000°C or higher, porosity is decreased.