The euro briefly hit 1.5575 dollars -- eclipsing its previous record high of 1.5570 set in New York on Wednesday -- before easing back to 1.5545 dollars in Tokyo late morning trade.
US President George W. Bush said the weakness of the greenback was "not good tidings" and that he backed a stronger dollar.
But market players said the US currency was likely to remain under pressure.
"The dollar is totally out of market favour now," said Kenichi Yumoto, vice president of foreign exchange sales at Societe Generale in Tokyo.
He said it was "fully possible" that the dollar would fall below the key 100 yen level.
Investors were reassessing Tuesday's move by the US Federal Reserve to inject 200 billio