The nation's foreign-exchange reserves hit a fresh record high in November.
The reserves rose $18.3 billion from October to $644.57 billion, mainly due to yen-selling intervention in the currency market, the Finance Ministry said Friday.
It was the third consecutive month of record highs, after a decline in August.
Yen-weakening intervention by Japanese monetary authorities during the month pushed up the foreign-exchange reserves. According to Finance Ministry data, Japan intervened to the tune of 1.6 trillion yen between Oct. 30 and Nov. 26.
A ministry official said the strengthening of the euro against the greenback during the month also pushed up the value of Japan's euro-denominated assets in dollar terms.
Although a decline in the value of U.S. bonds offset some of the increase, it was insufficient to affect the overall rise, the official said.
The previous record high for Japan's foreign-exchange reserves was $626.27 billion at the end of October.
Japan remained the largest holder of foreign reserves of any country or territory for the 48th straight month, the ministry said, citing the latest comparable data.
The foreign-exchange reserves consist of securities and deposits denominated in foreign currencies plus International Monetary Fund reserve positions, IMF special drawing rights and gold.