Japan's current account surplus fell by 19.5% in May, as the soaring price of oil boosted the value of imports, while Japanese exports remained stagnant.
Exports are a key driver of the Japanese economy
The surplus totalled 1.38 trillion yen ($12.4bn; $7bn) before seasonal adjustments, the finance ministry said.
Current account data measures the flow of goods, services and other financial transfers.
Weaker demand from Asia - and in particularly China - hit exports, a key driver of the Japan's economy.
Japan's trade surplus slumped 57.4% to 474.3bn yen, while exports rose just 1.7% to 4.58 trillion yen, official figures showed.
"The current account surplus fell sharply as import growth far outpaced export growth due to a rise in oil prices," a finance ministry official said.