Production of wrought copper and copper alloy products is expected to fall to 622,600 tonnes this financial year until March 31, down from 737,396 tonnes last year, the Japan Copper and Brass Association said.
The production figure, which has come lower than previous September forecast of 786,200 tonnes, will be the weakest since 1975 when the global oil shock in 1973-74 choked demand.
"Copper demand has been hit hard by a global economic slump amid the coronavirus pandemic," Shinji Ueno, the head of the research and statistics committee of the association, told a news conference.
"There are signs of recovery in semiconductor segment due to rising demand of electronic device as more people work from home, but demand from automobile and construction industries is expected to remain weak," he said.
The country's output last month fell 31.2% to 36,750 tonnes on-year, marking the 21st consecutive monthly decline and the lowest for August since 1967, the association said.
Japan consumed about 1.64 million tonnes of electrolytic copper and copper scrap in the 2018 financial year, 50% of which were used for electric wire and 45% for wrought copper, according to the non-ferrous metals data by the Ministry of Economy, Trade and Industry.
Last week, the Japanese Electric Wire & Cable Makers' Association slashed its forecast for the country's copper electric wire shipment for this financial year to 619,000 tonnes from its March estimate of 684,000 tonnes.
The revised figure will mark a 10.8% drop on-year and the lowest since the 1970 financial year.
(Reporting by Yuka Obayashi, Editing by Sherry Jacob-Phillips)