To provide a flat alkaline primary cell superior in cell capacity and capacity retention property.

In the flat alkaline primary cell 1 which includes a positive electrode mixture 5 containing a positive electrode active material, a negative electrode mixture 7 containing a negative electrode active material, and a separator 6 to separate the positive electrode mixture 5 and the negative electrode mixture 7, and contains an alkaline electrolytic solution in the positive electrode mixture 5, the negative electrode mixture 7, and the separator 6, this is constituted of the negative electrode active material composed of zinc or zinc alloy powder, and the positive electrode active material in which a surface of nickel oxyhydroxide wherein cobalt is solid-solved is coated with a conductive material.