Japan submitted to IAEA its annual declaration of holdings of civilian plutonium as of December 31, 2010 - INFCIRC/549/Add.1/14.
According to the document, at the end of 2010 Japan had 4,400 kg of separated unirradiated plutonium at the reprocessing facilities, 2,200 kg in unirradiated MOX fuel, and 2,900 kg in the MOX fuel manufacturing process. Additional 400 kg of unirradiated plutonium is "held elsewhere." In addition, Japan has 35,000 kg of unirradiated plutonium outside of its territory, down from 36,200 kg in 2009 (this the amount of material was described as 24,100 kg of "fissile plutonium" in the 2009 declaration).
Japan also declared 127,000 kg of plutonium contained in spent fuel held at reactors sites and 25,000 kg - in spent fuel at reprocessing facilities. Some material, less than 500 kg, is declared as held at other sites.