An alkaline primary cell which is improved in reduction of self-discharge and cell capacity under storage at a high temperature, has a prolonged life and makes use of nickel oxyhydroxide is provided inexpensively. .beta.-Form nickel oxyhydroxide is contained in a positive electrode mixture as an active material, which contains cobalt and zinc as a substitutional element for solid solution, and has a total amount X+Y of molar ratios of cobalt atom X and zinc atom Y such that 2.ltoreq.X+Y.ltoreq.16, with a mixing ratio satisfying the relationship of Y.ltoreq.3/2.times.X+1/2 and Y.gtoreq.2/3.times.X -1/3, and where a diffraction peak obtained as a result of measurement of X-ray powder diffraction of nickel oxyhydroxide appears only in the vicinity of 18.5.degree. within a range of 2.theta.=10.degree.-30.degree..