Nineteen samples of sediment collected from Tokyo Bay and coastal water along Fukushima Prefecture were analyzed radiochemically. The HCl-extraction efficiencies of radionuclides in sediment were examined. Recoveries of more than 80% were obtained for Ce-144, Ru-106 and Cs137 in fine mud collected in Tokyo Bay. The “shaver type” sampling device was designed to collected a large amount of sediment of the surface layer of 2 cm thickness. Sr-90, Cs-137 and Ce-144 concentrations in fine mud were remarkably higher than those in sandy mud or sand. It was clearly observed that ratios of Ce-144/Sr-90 and Cs-137/Sr-90 in coastal sediments were substantially higher than those in sea water. Ce-144 and Cs-137 were found to be accumulated more effectively in the surface mud on the bottom of the sea, in comparison with Sr-90.