The first new index, reporting January data, will be published on March 3.
The index, which covers the same type of goods and services as the Bank of Japan's index, would be useful in tracking consumer price trends as it excludes the effect of one-off factors that lead to temporary price fluctuations, the government said.
For monthly consumer price data, the government currently releases the overall consumer price index (CPI), the core CPI that excludes fresh food prices, and the "core-core" CPI that strips away the effect of all food and energy prices.
The new index - to be issued in addition to the government's existing ones - will include processed food prices.
It will be a good measurement of Japan's broad price trend, given the big impact processed food prices have on consumer inflation, the government said in a statement.
On Friday, the government said core CPI in December fell 0.2 percent from a year earlier, the smallest decline in nearly a year.
(Reporting by Leika Kihara; Editing by Richard Borsuk)