This study investigated the subcellular localization of radionuclide ,147,Pm in tissue cells by electron microscopic autoradiography. The early risk of internal contaminated accumulation of ,147,Pm was in blood cells and endothelial cells, especially in red blood cells where more numerous of autoradiographic tracks appeared. Then ,147,Pm was selectively deposited in ultrastructure of liver cells, such as in nucleus, nucleous, rough endoplasmic reticulum, mitochondria and microbodies. In organelleg ,147,Pm was mainly accumulated in rough endoplasmic reticulum and mitochondria. Autoradiographic tracks especially localized in combined point between Golgi complex and transitive vesicle of rough endoplasmic reticulum. Autoradiographic study also demonstrated, where dense tracks appeared in mitochondria and lysosome of podal cells within renal corpuscle. In nucleus as well as in mitochondria and microbodies within epicyte of kidney near-convoluted tubule where also more numerous tracks of ,147,Pm accumulated. With the prolongation of observing time,147,Pm was selectively and steadily deposited in subcellular level of organic component bone. Electron microscopic autoradiography showed, that substential amounts of ,147,Pm was taken up into the nuclear fraction of osteoclasts and osteoblasts. In addition, where more numerous tracks of ,147,Pm was deposited in collagenous fibre within interstitial of bone cells and was hardly excreted.