This report presents the results on the measurements of plutonium in samples of various human organs of Japanese collected in Niigata prefecture since 1963 to 1973. The results showed that the averaged concentrations of Pu-239+240 in cerebrum, lung, heart, liver, spleen, kidney, testicle, uterus, ovary and bone were 0.5, 1.2, 2.3, 0.8, 1.1, 0.6, 0.9, 0.8, 3.4 and 2.7 fCi/gram fresh weight respectively. Although it is suggested that liver and bone are the critical organs for plutonium intake, it can not be overlooked the accumulation of this nuclide in spleen and gonad. As the amount of plutonium deposited in organs showed a closer relation to the intake of the nuclide in the atmosphere than in the diet, it should be said that the greatest care have to be taken to the inhalation of this nuclde.