The year-on-year September increase in the core CPI, which excludes volatile fresh food prices, was off slightly from 0.8 percent in August, but represented the fourth consecutive monthly increase, the Ministry of Internal Affairs and Communications said. 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.
As part of that effort, 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.
The September increase was largely due higher electricity and gasoline prices and increases in some durable goods prices.
The Financial Times said the source of the current inflation is a weak yen which pushes up import costs, and not significantly stronger domestic demand for goods. However, a weaker yen also helped boost Japan's exports, it said.