 "Nikkei edges down before BOJ; Fujifilm extends gains on Ebola cure hopes")
The central bank is likely to maintain its massive monetary stimulus and offer a bleaker view on factory output.
The Nikkei share average dropped 0.1 percent to 15,871.27 in midmorning trade after rising 1.2 percent on the previous day.
BOJ Governor Haruhiko Kuroda will appear in parliament before the upper house budget committee on the same day from around 10:20 a.m. to 11:40 a.m. (0120 to 0240 GMT), a parliamentary source said.
"This is a rare case in which the BOJ governor appears at the parliament on the day when its policy meeting is held. There is speculation that the governor may be pressured (for additional easing) by politicians," said Hikaru Sato, a senior technical analyst at Daiwa Securities. "The market is taking a wait-and-see stance."
Fujifilm Holdings Corp stood out, outperforming the market and extending its prior day gains - up 7.8 percent at 3,774.0 yen, the highest level since June 2008.
The company said on Monday the French and Guinean governments are considering clinical trials using its influenza drug Favipiravir developed by its group firm Toyama Chemical Co. to treat patients infected with the Ebola virus.
"I started buying the stock when the news about the first patient in the U.S. came out," said a fund manager at a Japanese asset management firm, tipping more upside toward 5,500 yen.
"If a panic spreads to other regions, it could hurt the global economy. I would keep Fujifilm among our top picks," he added.
Exporters were mixed, with Toyota Motor Corp gaining 0.5 percent, Honda Motor Co adding 0.1 percent and Toshiba Corp shedding 2.8 percent.
The broader Topix rose 0.2 percent to 1,299.22, and the JPX-Nikkei Index 400 added 0.2 percent to 11,802.81.