The August increase, largely due to higher energy prices, was the third straight monthly gain and the highest jump since November 2008 when prices rose 1 percent. The core consumer price index, which excludes fresh foods, was released by the Ministry of Internal Affairs and Communications on its website.
Prices rose 0.4 percent in June and 0.7 percent in July.
The government of Prime Minister Shinzo Abe has put in place several stimulus measures to pull the economy from 15 years of chronic deflation or falling prices. The measures already have helped weaken the yen against major currencies, thus boosting critical Japanese exports.
The Bank of Japan has doubled its inflation target to 2 percent to be achieved in the next two years, with plans to inject billions of yen into the economy.