It rose to 83.4 yen versus the dollar, adding to fears that Japanese goods are becoming uncompetitive.
Japan's finance minister Yoshihiko Noda, had suggested that he would take measures to push the yen lower.
But investors ignored the comments, and continued to push the yen higher.
He promised to act firmly if necessary, saying that "in the end, we will take decisive measures including intervention when needed".
Meanwhile figures showed a strong rise in Japanese machinery orders in July, up by 8.8 per cebt, but these did not ease concerns over the damage being caused to the export sector by the yen's strength.