The monetary base in Japan jumped 3.7 percent in May from a year earlier, the Bank of Japan (BOJ) said in a report on Wednesday.
The monetary base stood at 98.432 trillion yen (1.078 trillion U.S. dollars), up from 98.383 trillion yen on year in April, according to the report.
May's monetary base was higher than median estimates for a 2.8 percent annual increase in the recording period, following the 2.9 percent gain in April.
Banknotes in circulation were up 0.6 percent on year, although coins in circulation declined an annual 0.4 percent, the BOJ said.
Current account balances surged 22.9 percent on year, including an 18.6 percent annual leap in reserve balances, the figures showed
On a seasonally adjusted basis, the monetary base rose 12.4 percent in May to 97.479 trillion yen (1.068 trillion U.S. dollars) , following an 18.1 percent rise in April.
Japan's monetary base refers to the amount of currency that is either circulated in the hands of people living in Japan or in domestic commercial bank deposits held in the central bank's reserves. This measure of the money supply typically only includes the most liquid currencies.
The Japanese administration maintains a measure of control over the monetary base by buying and selling government bonds in the open market.