[en] The samples of rain and dry fallout, air-borne dust, service water and fresh water, soil, sea water, sea sediment, total diet, rice, milk, vegetables, tea, fish, shellfishes and seaweed, and fresh water fishes, their sampling and prior treatment are described. The methods of separating Sr-90 and Cs-137 and their measurement are explained. The estimations of stable Sr, K and Ca are made by atomic absorption spectroscopy, flame spectrophotometry and potassium permanganate titration, respectively. The general plan of radioactivity survey in Japan is shown. As the environmental data, the results of Sr-90 and Cs-137 in sea sediment obtained from April, 1978, to March, 1979, and the locations of sampling are given. In a table, the months and the locations of sampling, depth (m), and the amounts of Sr-90 and Cs-137 (pCi/kg) are shown. The maximum values are 17 pCi/kg of Sr-90 found in Mutsu Bay and 180 pCi/kg of Cs-137 in Ajisu, Yamaguchi Prefecture, in August, 1978. (Kako, I.)