Mr. Abe’s promises of economic revival have already created a budding optimism in urban areas like Tokyo, where the stock market has rallied and restaurants seem more crowded than they were during years in which many people resigned themselves to Japan’s fading prospects. The new, if fragile, hopefulness has been boosted by rising corporate profits, as a weakening yen has brought desperately needed relief to badly shaken electronics corporations and other exporters struggling to compete with Chinese and Korean rivals.

The yen has dropped 20 percent in recent months, on the strength of Mr. Abe’s promises to rethink Japan’s priorities.

While the new prime minister is off to a strong start, political analysts said it was too early to tell if he will be the rare decisive Japanese leader who can make a real impact, like his mentor, former Prime Minister Junichiro Koizumi, whose liberalizing policies Mr. Abe is apparently seeking to continue.

Economists say the jury is still out on whether Mr. Abe’s measures, popularly called Abenomics, will be drastic enough to restore growth to a $5.9 trillion economy that in yen has shrunken back to the same size it was in the early 1990s and caused the country to slip behind China on the list of the world’s largest economies. (The current ranking is the United States first, followed by China and Japan.)

Mr. Abe started his push for changes at the Bank of Japan less than a month after taking office in December, pressing its leaders to set a target of causing rising prices, or inflation, at a rate of 2 percent per year. When the bank failed to follow quickly with bold measures to accomplish that goal, Mr. Abe’s Liberal Democrats threatened to rewrite the law to make the bank more obedient.

That was enough to drive the incumbent central bank governor, Masaaki Shirakawa, who has long been criticized for inaction, to announce that he would step down three weeks earlier than planned. On Thursday, Mr. Abe nominated his replacement, Haruhiko Kuroda, an Oxford-trained former Finance Ministry official.

Even Mr. Abe’s own economic advisers say it is unclear what Mr. Kuroda will do, and point out that he is more cautious than other people whose names were floated as possible replacements for Mr. Shirakawa. Still, at parliamentary hearings on his nomination on Monday, Mr. Kuroda pledged to do “whatever it takes to escape from deflation,” without giving specifics.