With the preparation to study on the fate of iron isolated from the decompostion process of hemoglobin in vivo since the distribution of ferritin in organs, the apoferritin quantitative method by L. Heilmeyer and others, as a quantitative methode of ferritin in organ, was investigated and the apoferritin dosis in the liver, kidney and spleen of healthy rabbits were measured. And the results were as follows. 1. The material was suitable to use that concentrated for 30-40 minutes by the water jet pump until it was almost dried, in boiling water at 40-60°C., at the end step. 2. As for the condition of paper electrophresis, it was the most suitable to make the migration by the fixed electric pressure of 25 volt to the 1 cm width of filter-paper of Schleicher & Schüll No.2043a for 24 hours. 3. The measurement became easy and accurate by the farther coloring of the stained area with ammonia gas before the fixation of filter-paper by solid paraffin. 4. The degeneration of material made an error on the paper electrophoresis of apoferritin, but the error was not observed on the material by this improved method. 5. The appearance rate of apoferritin in 1g of liver, kidney and spleen of healthy rabbit was 7.6, 7.8, 6.4.