Bank of Japan officials say in September the cost of goods traded among companies hit a 13-year high.
They say the main factor was rising crude oil prices.
The central bank officials say the producer price index rose 6.3 percent in September from the same month last year. It's been climbing for seven months in a row and is at its highest point since August, 2008.
The officials also point to steeper electricity fees for offices, and climbing prices for petroleum products.
Both trends are a result of growing demand from economies that continue to recover around the world.
The impact on prices for steel, lumber and other raw materials has been largely the same.