1) Based on the systematic experimental ground about explanatory tasks for Misestimation of indican, I have invented a new microestimation method for indican found in the blood. 2) Normal value of blood indican estimated due to new method for superseded those various theories hitherto proclaimed, reached so high as 0.261 mg% at highest, while proved at lowest 0.099 mg% ; average, 0.190 mg%. 3) Complete estimation of blood indican is difficult by using of most estimation method for blood indican in which Jolles's reaction has been adopted as principles. 4) The necessity of re-examination for those various achievement as to clinical significances of blood indican thus clarified hitherto, by using new exact estimation method, has become urgent.