In view of the fact that surface reactions of plasma treatment are initiated by plasma-induced surface radicals, study of such radicals is of utmost importance for understanding of the nature of plasma treatment. Since each parameter to specify the plasma eventually affects the intensity of plasma, "plasma power'', to generate the surface radicals, we have examined to develop the method to deduce the plasma power useful for experimental and practical designs of plasma treatment. In the light of the special features of plasma-induced polycrystalline myo-inositol radicals, we report here that measurement of such a radical formation can be used as chemical diagnostic tool for plasma power.