Disclosed is an electrolytic manganese dioxide having an alkali potential of at least 310 mV, a full width at half maximum of the (110) plane in the XRD measurement using the CuKα line as the light source of from 2.2o to 3.0o, and a (110)/(021) peak intensity ratio in the X-ray diffraction spectrum of from 0.5 to 0.80. Also disclosed is a method for producing electrolytic manganese dioxide by electrolysis in an aqueous solution of a sulfuric acid/manganese sulfate mixture.