Japanese shipments of aluminium products fell 7.6 percent in April from a year earlier to 163,805 tonnes, industry data showed on Wednesday.
That was down 4.3 percent from 170,878 tonnes in March, data provided by the Japan Aluminium Association showed.
It was the first full month of data since the March 11 earthquake and tsunami devastated the nation's northeast coast, damaging roads, ports and other infrastructure and disrupting supply chains.
Effects of the disaster had already been reflected in March aluminium product shipments, which fell 8.5 percent from a year earlier to log the first year-on-year decline in 16 months.