Crude steel output, which is not seasonally adjusted, declined to 8.16 million tonnes in October from a year earlier, although it was up 1.5% from September.
Japan's biggest steelmaker, Nippon Steel Corp, said last month that one of the two steelmaking plants at its Kimitsu Steel Works near Tokyo would be shut until the end of December to repair a chimney that collapsed in a typhoon in September.
Another plant at Nippon Steel's subsidiary in Hiroshima, Kure Works, has also suspended operations since a fire damaged its operating room in late August.
Japanese steelmakers trimmed their annual profit forecasts earlier this month as slumping steel prices in Asia eroded their export margins, while slower auto demand overseas and falling usage in machinery at home forced them to cut output.
They are suffering from a softening global economy hit by the U.S.-China trade row and rising costs of raw materials such as iron ore as top producer China boosts crude steel output to meet infrastructure demand and support its economy.
By Yuka Obayashi