In the month-long devaluation run, the Japanese yen temporarily broke through the 150 yen per dollar mark on Thursday, thereby intensifying speculation about a new foreign exchange market intervention by the Japanese government.
The Japanese currency was traded briefly at 150.09 yen per dollar.
The last time the yen was this cheap was 32 years ago in August 1990.
Since the beginning of the year, the yen has lost around 30 percent in value as a result of the monetary policy discrepancy between America and Japan.
Patrick Welter
Correspondent for business and politics in Japan based in Tokyo.
Follow I follow
"We cannot tolerate excessive and rapid movements as a result of speculative trading in the foreign exchange market," Finance Minister Shunichi Suzuki told journalists. The minister warned that the government will act decisively if necessary. But on Thursday, it appeared that the government would not sold dollars in the market Suzuki declined to comment on the level of the exchange rate.
For weeks, the government and the central bank have been following the line that abrupt exchange rate fluctuations are undesirable, without committing to an appropriate exchange rate level.
In September, the government had sold about $20 billion when the exchange rate hit 145 yen per dollar.
This only stopped the devaluation trend for a short time.
Market observers argue that the depreciation run will only end if selling pressure on long-dated US government bonds eases or if the Bank of Japan ends its loose monetary policy.
But central bank governor Haruhiko Kuroda rejects this.
On Thursday, the central bank continued to buy additional government bonds to ease upward pressure on Japanese interest rates and keep the 10-year interest rate in the minus 0.25 to 0.25 percent range.
No change in monetary policy is expected for next week's central bank meeting.