Radio-active isotopes were widely deposited over large area of forest in Japan as a result of the Fukushima Daiichi nuclear power plant accident. Among them, radioactive cesium is an issue of great concern, because it will be long time recycled in forest ecosystems. Two mesh sizes (fine mesh: 0.17 mm and coarse mesh: 2 mm) litterbags containing 16 g of mixed deciduous leaves (mainly Quercus serrata) were set at a deciduous forest in Fukushima, in December 2011. Weight loss, 134Cs, 137Cs, total C, N, and stable Na, K, Rb, Cs, Mg, Ca, Sr, Ba and Al concentrations were monitored from April to December 2012. Radio-Cs concentrations rapidly increased after April and reached its maximum on October in the both mesh bags, and it was 4 to 5 times higher than surface soil (0-5 cm) contamination. The coarse mesh bags showed ca. 20% higher concentration of radio-Cs than that in the fine mesh bags. Fungi are known as accumulators of radio-Cs. The trend pattern of radio-Cs was as same as fungal PLFA in litter, but not bacterial PLFA. In litter samples, good correlations were observed among the concentrations of radio-Cs, P, Zn and Sr. In contrast, radio-Cs was not correlated with K in the litter.