The soybean ( Glycine max L. ) root cultured under iron deficient condition was employed as the experimental material in order to raise the ferric reductase content in root. The method is chemically based on the reduction of ferricyanide by ferric reductase to ferrocyanide from which, in presense of cupric ions, an insoluble and electron-dense brownish precipitate is formed. For better observation under light microscope, the dull brown precipitate was converted into black silver precipitate of sharp-contrast using the sulfide-silver amplification method. With this method, accurrate and specific localization of ferric reductase was obtained. Under electron microscope, the dense enzymic reaction product was found as fine granules covering the plasmalemma which was in consistent with the results obtained by biochemical method. The present method for the localization of ferric reductase is more accurrate than the prussian blue staining method, because the brown precipitate in this method is finer than the prussian blue precipitate. Further, the pH 6.6 of the reaction medium is closer to the optimum pH of 5.5 to 6.5 of ferric reductase activity whereas the pH of the prussian blue staining solution is only 3.