Taro Aso, who also serves as deputy prime minister, said bankers in Japan had not been able to understand the complex financial instruments that were the undoing of major global players, so had not bought them.
"Many people fell prey to the dubious products, or so-called subprime loans. Japanese banks were not so much attracted to these products, compared with European banks," Aso told a seminar in Tokyo.
"Managers of Japanese banks hardly understood English, that's why they didn't buy," he said.
Aso's comments Friday are the latest in a line of pronouncements that have raised eyebrows.
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The one-time prime minister said in January the elderly should be allowed to "hurry up and die" instead of costing the government money with expensive end-of-life medical care.
In 2007 he had to apologise for a quip about patients with Alzheimer's disease and for making light of flood damage in central Japan.
But the deputy prime minister, who is known as a dapper dresser and often seen sporting a jauntily-angled hat, on Friday boasted he had managed to keep his foot out of his mouth since Shinzo Abe came to power as premier in December.
"I have made no gaffes in the past half year even as newspapers said the Aso administration's... No, the Abe administration's biggest problem is Taro Aso's gaffes," he said.