The Bank of Japan has increased its stimulus programme for the second time in two months in a bid boost the country's economic growth.
The bank said it would expand its purchase of government bonds by 10 trillion yen ($US123 billion).
Japan's economy is struggling amid a slowdown in key export markets such as the United States and the eurozone and weak domestic demand.
The BoJ also left its key interest rate unchanged between zero and 0.1%.