Shoichi Nakagawa at the news conference
Japan's Finance Minister Shoichi Nakagawa has resigned, amid claims that he was drunk at a recent G7 meeting.
Mr Nakagawa said earlier that he would wait until parliament had approved a supplementary budget to step down.
But he brought forward his departure after calls for his immediate exit escalated.
Prime Minister Taro Aso said he respected Mr Nakagawa's decision and named Economics Minister Kaoru Yosano to take over the finance portfolio.
At a news conference just hours after his appointment, Mr Yosano said the country's economy had deteriorated "beyond expectation".
Mr Yosano said his priority was to "smooth" the financial system as well as stimulating demand.
He said he would decide whether to take additional steps after consulting not only the government but business leaders, academics and the media.
Mr Nakagawa's departure is seen as a major blow to Mr Aso's government in an election year.
The prime minister was already facing plummeting support; a poll by broadcaster NTV on Sunday put backing for his cabinet at 9.7%.
Voters are worried both about the economy and Mr Aso's leadership credentials in the wake of a series of gaffes, analysts say.
Mr Nakagawa apologised for "causing such a big fuss" and told journalists: "I decided that it would be better for the country if I quit."
He has already apologised for his behaviour at last weekend's news conference in Rome but blamed cold remedies for a slurred performance there.
He said he had not drunk more than a sip of alcohol before facing the media.
The news conference in Rome followed a meeting of finance ministers focussing on the current world economic crisis.
Footage showed Mr Nakagawa slurring his speech and closing his eyes repeatedly as if he was dozing off.
At one point, he mistook a question aimed at the governor of the Bank of Japan as one intended for him.
"It's embarrassing," said Democratic Party Secretary General Yukio Hatoyama. "This has sent a message to the whole world. He's damaged the national interest."
He explained that he had sipped wine at a luncheon toast on the day of the news conference, but had not consumed an entire glass.
He said he had taken too much medicine, including cold remedy, and that had made him drowsy.
Mr Nakagawa has denied reports - including the view of a former prime minister - that he is a regular drinker.