Japan officially fell into recession last year and there was a dramatic fall in growth in the January-March period as the world economic slowdown hit Japanese exports hard.
Government stimulus measures totalling $260bn (£159bn) helped to boost the economy, including cash handouts and subsidies to buy energy-efficient cars and home appliances, the BBC's Roland Buerk in Tokyo says.
Manufacturers also benefited from recovering demand in China and other markets, with overall exports up 6.3% during the quarter.
But Japan could still face a long road to sustainable recovery, our correspondent says, with domestic private consumption rising only 0.8% despite the stimulus measures.
Seijiro Takeshita, director of Mizuho Financial, Japan's second largest banking group, told the BBC that the Japanese economy was now staging a "true comeback".
"We are definitely getting out of the excessive pessimism that we have been seeing... however, a lot of big questions remain, namely private consumption," he said.
"We know this time it was good, but that was due to a lot of government stimulus spending."
Mariko Oi, reporter, BBC Asia Business Report
Appetite for Japanese cars is slowly recovering around the world, thanks to government schemes to encourage people to replace their old vehicles.
Overall Japanese exports grew 6.3% in the second quarter from the previous three months. That's reduced stockpiles of goods, and encouraged firms to start producing again.
Consumers are also starting to spend thanks to the stimulus package worth $260bn.
But people are still losing jobs. The unemployment rate continues to rise, and is expected to hit a record 5.8% next year.
That is why analysts say it will be a long road to a sustained recovery.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.