Japan's foreign exchange reserves totaled $362.61 billion as of the end of April, up $1.139 billion from the month before, the Finance Ministry said Wednesday.
This marks the first increase in three months, according to the ministry.
The rise was attributed mainly to the euro's strengthening against the dollar, which helped boost the value of euro-denominated assets.
In February and March, the weak euro played a key role in suppressing the reserves, which consist of securities and deposits denominated in foreign currencies, International Monetary Fund reserve positions, IMF special drawing rights and gold.
At the end of April, Japan had $283.31 billion in foreign securities and $65.58 billion in foreign currency deposits.
Of the latter, $5.70 billion is stored in foreign central banks and the Bank for International Settlements, $38.89 billion is stored in Japanese banks and $20.98 billion is stored in foreign banks.
Japan also had $4.91 billion in IMF reserve positions, $2.35 billion in IMF SDRs and $6.46 billion in gold.
Based on data available at the end of February, Japan was the largest holder of foreign reserves of any country or territory for the 17th straight month.