A method of producing high concentrated 99mTc solution has the steps of dissolving 99MoO3 pellet with alkali solution extracting 99mTc from the dissolved solution with ketone type organic solvent separating an ketone type organic phase containing 99mTc and an aqueous phase adsorbing and concentrating the separated ketone type organic phase containing 99mTc after removing impurities, through a basic alumina column for impurity removal and an acidic alumina column for adsorption and concentration connected continuously and eluting 99mTc from the acidic alumina column to which 99mTc is adsorbed by physiological saline, wherein the alkali solution is 6M-NaOH solution or 6M-KOH solution.
