The January-March gross domestic product growth from the previous was revised from the previous 0.9 percent, or an annualized rate of 3.5 percent, the Cabinet Office reported Monday.
The Cabinet Office also revised upward first-quarter corporate capital spending to negative 0.3 percent from the negative 0.7 percent reported May 16.
In its May report, the Cabinet Office had credited the first-quarter results to healthy consumer spending and higher exports. Monday's data did not revise quarterly export growth of 3.8 percent and import growth of 1 percent.
Analysts speaking to Kyodo News credited Japan's export growth to signs of recovery in the U.S. economy and Prime Minister Shinzo Abe's economic policies that include aggressive monetary easing by the central bank and massive public spending. The policies have already helped stem the rising yen, which helps boost exports.
The Abe government has made it a priority to pull the country out of chronic deflation and kick-start the world's third-largest economy through various stimulus measures. Japan's central bank has already doubled its inflation target to 2 percent.
The Nikkei-225 stock index, responding to Monday's development, was moving higher in early trading on the Tokyo Stock Exchange.
The Financial Times said the upward revision of the GDP would also help the effort of Abe's Liberal Democratic Party to win a majority in the upper house during the July 21 elections, which would pave the way for his government to press on with its economic reforms.