To examine the translocation of radiocesium scattered by the Fukushima Daiichi nuclear power plant accident that occurred in March 2011 to the Japanese chestnut, we investigated the autoradiography and radiocesium concentration in each part of Japanese chestnuts. The Japanese chestnut fruit has a thin skin between the kernel (cotyledons) and shell; the kernel of the fruit is edible. The Cs-137 concentration in each part of the fruit was found to be almost the same at about 1.0 x 10(4) Bq.kg(-1) DW, as well as leaves. The radiocesium concentration in chestnut weevil larvae found on the fruit was approximately one-seventh of that in the kernel.