TOKYO - In the first sign that the bold policies of Prime Minister Shinzo Abe are gaining traction in the real economy, Japan's gross domestic product grew at a robust annualized pace of 3.5 percent in the first quarter, kindling hopes that recovery would finally take hold for the long-suffering economic power. Japanese growth came to 0.9 percent for the January-to-March period compared with a year ago, driven by higher household consumption and exports, government data showed Thursday. Personal consumption, which makes up the largest part of Japan's G.D.P., grew 0.9 percent, as consumer sentiment brightened amid signs of an economic recovery. Capital expenditure fell 0.7 percent for the fifth consecutive quarter, though economists expect a rebound as the recovery takes hold. Public spending grew 0.8 percent. The solid pace, which followed two quarters of contraction and a quarter of just 0.2 percent growth, appeared to point to the beginnings of a long-awaited turnaround in the Japanese economy, the world's third-largest, after those of the United States and China. "It is a sign that the Abe administration's economic policies are starting to show results," said the economics minister, Akira Amari. The latest numbers have come as early validation for Mr. Abe, who took office in December and has used what has been called a "three-arrowed" bid to lift Japan out of its long deflationary slump. He has focused on an aggressive monetary policy that has flooded the economy with cheap money, major fiscal spending and changes to make the economy more competitive. This first arrow has been accompanied by a devaluation of the yen by about 20 percent in the past six months, which has been a boon for exporters. Exporters including Toyota and Sony have reported a rebound in profit in the first quarter of 2013, thanks in good part to the policy. In recent days, however, concerns have grown about rising interest rates in the government bonds market, which could threaten Japan's monetary policy. Bonds are also the main financial asset held by banks, pension funds and insurance companies, making a surge in debt yields perilous. The Nikkei stock index has risen an astonishing 46 percent since Mr. Abe took office. And though the improved fortunes of exporters and the surging stock market have yet to translate to higher wages, there are signs of brighter consumer sentiment and a recovery in spending, which will be critical to Japan's fight against deflation. Japan is also getting help from the second arrow, more fiscal spending. Mr. Abe pushed through an emergency stimulus package of ¥10 trillion, or $97 billion, in February and has followed up with a ¥92.6 trillion initial budget for 2013, which Japan's Parliament approved late Wednesday. That heavy spending is expected to push up growth next quarter. Economists at Nomura, the Japanese investment bank, said they now projected strong growth for three consecutive years, with an estimated 1.6 percent expansion for the whole of 2013 and even higher growth after that. Sentiment among companies and consumers has improved sharply of late as the yen has depreciated and the equity market has risen. We think this is likely to create a positive cycle in which improved sentiment underpins growth in private consumption and private capex," Nomura said in a research note after the figures were released, referring to capital expenditure, "and this growth in turn supports further improvement in sentiment." Beating deflation remains, for now, an elusive goal. The G.D.P. deflator, a measure of the average price of all of the goods and services produced in an economy, was negative 1.2 percent, year on year, though economists said they expected deflation to ease gradually as benefits from the weak yen were felt more widely throughout the economy. And economists warn that for the economy to keep growing, the third arrow will be crucial: mainly structural changes that aim to make the economy more competitive, for example by making Japan's labor market more flexible and lowering barriers to trade. But these changes will be far more politically difficult for Mr. Abe to push through. "We expect Abe's first and second arrows to support domestic demand significantly in the next two years," the UBS economists Daiju Aoki and Toru Ibayashi said in a recent note. "That said, the two policies can only stimulate short-term demand-side growth, not long-term fundamental growth," they added. "For the rally to continue and be fundamentally driven, Abe must convince the market that his "third arrow" will benefit Japan's underlying economy."