After a two-day meeting on Friday, the BoJ left its benchmark interest rate unchanged at-0.1 per cent and its 10-year yield target around 0 per cent, in line with market expectations.
The BoJ cut its growth forecast for the current fiscal year to 3.8 per cent from 4.0 per cent in April.
Japanese President Toshihiko Kuroda is expected to hold a press conference at 3:30 local time.
The BoJ left its main policy settings unchanged and outlined details of climate-related financing measures, but did not offer to pay interest to banks to encourage them to "go green".
The Bank of Japan said in a statement on Friday that it would grant more negative interest rate exemptions to banks if they provide loans or investments to the green economy. Most economists had expected the central bank to go further and proposed paying a small amount of interest.
For weeks, the market has been speculating about how the Bank of Japan will design the green loan program it hinted at last month; on Friday, the bank finally outlined the measure, which in principle will last until the end of fiscal 2030.