Economic and fiscal policy minister Heizo Takenaka suggested Sunday that several trillion yen would be needed to sufficiently increase the money supply if the Bank of Japan buys exchange-traded funds on the market.
"We'll need a sufficient amount of money," Takenaka said on a TV Asahi talk show, but he added that he wants policymakers to "boldly discuss" the plan's implementation.
BOJ officials and some experts are concerned that attempts to bolster the nation's sagging stock market by using public money to purchase such funds will increase the central bank's exposure to market risks.
ETFs are funds that track core equity indexes and allow investors to buy a basket of shares in one transaction. They trade like stocks and are a riskier form of investment than government bonds because of their volatility.
While noting that momentum has been growing among politicians to introduce an inflation target to stem falling prices, Takenaka said it is also important to discuss how to "boost the money supply at a steady pace."