For the purpose of applications to the determination of the most appropriate soil stripping thickness in case of radioactive decontamination or in situ measurement of radioactivity in the soil, we have developed a monitor which measures depth distribution of radioactive cesium concentration in the soil. In this study, we describe the configuration of the monitor and the estimation method of soil-radioactive depth distribution from the counting rates of multilayered CsI(Tl) detectors and a NaI(Tl) detector coupled with unfolding technique. Based on the measurement of radioactive reference sources, our developed monitor is useful to determine the soil thickness for radioactive decontamination. It could help to decrease extra radioactive soil at storage areas and to speed up radioactive soil decontamination.
